Slow Cooker French Onion Soup

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Slow Cooker French Onion Soup is one of our favorite meals to come home to!

As with any traditional French onion soup, this recipe features a beefy broth loaded with caramelized onions and herbs and topped with an amazing Gruyere cheese topping!

The perfect meal for any soup lover!

French Onion Soup features sweet caramelized onion in a rich beefy broth. This meal cooks up effortlessly in the slow cooker all day!


French Onion Soup is one of my husband’s all time favorites.

For me it’s all about the bread and cheese…  all soaked in that rich herby onion broth and then broiled until the cheese gets all hot and bubbly.

Scooping up the first bite of that ooey gooey cheese is like a little taste of heaven.

While French Onion Soup is good, I do think that a good broth takes a long time to develop great flavor which is something I love about this recipe.

In this easy Crock Pot recipe, the onions and broth have the chance meld in the slow cooker all day long creating a rich and flavorful soup.  Not to mention, I’m a huge fan of slow cooker meals because I love coming home to dinner ready to go!

It just seems to make the evening run that much smoother, at least in my house with activities, homework and soccer practices!


Why do they Call It French Onion Soup?

French onion soup actually originated in France in the 18th century and has been a traditional soup of France ever since.  This soup is most often served as a starter however we love to enjoy it (with extra bread and a salad) as a meal.


How do you Make French Onion Soup from Scratch

To make french onion soup completely from scratch you’d want to start with your own homemade broth or stock. While I often make chicken broth from scratch for this recipe I usually use a lower sodium store bought broth.  Either will work just fine.

Caramelizing the onions does take a little bit of time but it’s totally worth the effort.  You want them translucent and golden without browning or crisping them so low and slow heat is the way to go with these!  You don’t have to stir them constantly but you do want to make sure they aren’t cooking too quickly.

While I caramelize them on the stove top for convenience, you can actually caramelize them right in your slow cooker too but it does take 8-10 hours!  If you get them started the night before, you can wake up to caramelized onions, add the remaining ingredients and you’re good to go!

To Caramelize Onions in the Slow Cooker

Combine 3lbs sliced onions, 1/2 cup unsalted butter and 1/2 teaspoon salt.  Stir and cook on low 8-10 hours.  (You would need half of these onions for this recipe but can add more if you like. You can freeze the other half to add to mashed potatoes, casseroles, soups and more). (Note you do not need brown sugar if you use this method, the onions have enough natural sugars).


What is the Best Onion to Use in French Onion Soup

When making French onion soup, you’ll want an onion that will caramelize well and have the right amount of sweetness.

I find using regular white onions provides the best results as sweet onions can overpower the broth and tend to create a soup that is too sweet.

If you happen to have only sweet onions on hand, I would suggest eliminating any sugar from the recipe.

What kind of cheese is best for French Onion Soup?

The bread and cheese topping is one of my favorite parts of this recipe.  Using Gruyere and Emmental cheeses really makes this dish amazing however, you can substitute mozzarella/ parmesan/ swiss if it’s all you have on hand.

I love to ladle this into bowls, add the cheese and broil however you can simply place the bread & under a broiled on a pan and add it to your bowls if you prefer.

Serve this French Onion Soup with a side salad and some extra bread for a delicious dinner!

Slow Cooker French Onion Soup

Slow Cooker French Onion Soup is one of our favorite meals to come home to! A rich beefy broth loaded with caramelized onions and herbs and topped with an amazing Gruyere cheese topping!

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  • 3 large white onions , sliced
  • 3 tablespoons butter
  • 2 tablespoons brown sugar
  • 64 oz Beef Broth (I use reduced sodium)
  • 1 tbsp Worcestershire sauce
  • 1 clove garlic , minced
  • 1/3 cup dry sherry
  • 4 sprigs fresh thyme (or 1 tsp dried Thyme)
  • 1 Bay Leaf
  • 8 slices dry french bread
  • 3/4 cup Gruyere cheese , shredded
  • 1/2 cup Emmental cheese , shredded
  • 6 tablespoons fresh parmesan cheese


  1. In a large non-stick pan, cook onions, butter and brown sugar over medium low heat until golden and caramelized. (About 20 minutes).
  2. Once golden, add to the slow cooker along with remaining ingredients except bread and cheeses.
  3. Cook on low for 6-8 hours.
  4. Remove and discard bay leaf and ladle the soup into bowls. Top with dry bread slices and cheeses. Broil 2-3 minutes or until cheese is melted and browned.


If you don’t have dry bread, slice your loaf and dry it in the oven at 300 degrees for about 5-7 minutes. Cool completely.

Nutrition Information

Yield: 8 servings, Serving Size:

  • Amount Per Serving:
  • Calories: 537 Calories

(Nutriton information provided is an estimate and will vary based on cooking methods and brands of ingredients used.)

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Slow Cooker French Onion Soup is one of our favorite meals to come home to! A rich herby onion broth topped with cheese and broiled until hot and bubbly.
Slow Cooker French Onion Soup is one of our favorite meals to come home to! A rich herby onion broth topped with cheese and broiled until hot and bubbly.


How to Make Slow Cooker French Onion Soup

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Holly is a wine and cheese lover, recipe creator, shopping enthusiast and self appointed foodie. Her greatest passion is creating in the kitchen and making deliciously comforting recipes for the everyday home cook!

98 comments on “Slow Cooker French Onion Soup”

  1. HI




  2. Your recipe is exactly what I am looking for. I can try making a new delicious dish for my family. Thank you for your recipe

  3. My BFF & I love French onion soup. Will be having her for lunch Thursday and im gonna make your recipe. One ? Though. Do you think it would be possible if I carmalized the onions with the brown sugar the night before & then warmed them in the microwave the following morning before adding them to the crock pot ? Just looking to save a little more time in the morning if possible.

  4. In the crock pot now!! So excited.
    Have you tried to make it on high at all?

  5. What would be a good substitute for the Sherry?

  6. You can carmelize the onions in the slow cooker, then added the rest of the ingredients and continue to cook. Delish

  7. Thanks for the recipe. We love French Onion soup. I did try the recipe, though, and the brown sugar made it too sweet. I will leave that out next time.

  8. I never heard of emmental cheese. Is there ant other kind of cheese you can use.?

  9. Hiow do you print off receipes from your site>?

  10. Please send me the recipe for French onion soup

  11. Would any type of onion work? Could I use Vidalia? Looks great, making it for dinner tonight and hoping I don’t have to run to the store.

  12. Made this tonight & it was amazing! I followed the directions as instructed. Wouldn’t change a thing it was so damn good!!!

  13. I love y’all’s website

  14. How many calories per serving?

  15. Do I have to use the Sherry or is that a personal preference for you?

  16. When it comes to cooking with wine, I always shy away from it, because I am totally ignorant when it comes to picking wine for cooking! I never know what wine to use, so can I leave it out? Thank You!

    • You can leave it out but it really does add nice flavor. Cooking sherry is sold in the grocery stores near the vinegars and olive oils and there are only usually a couple of brands to choose from.

      For whites, I use an inexpensive bottle of dry crisp white such as a Pinot Grigio or Sauvignon Blanc.

  17. Can you tell me how many carbs are in this soup without the bread? Looks delicious but I’m on a low carb diet.

  18. Could you tell me what the calorie intake is for a cup of soup?

  19. Good morning.
    I’m so anxious to try your soups, especially the French onion. I’m confused about the amount of onion. One place it says 3 pounds and another place it says 3 onions.
    I saw so many others to try also
    Thank you

  20. I have this in the crockpot now !! I bought sherry cooking wine at the grocery store . Is that the same as dry sherry??? I don’t want to mess this up!!!

  21. Just a wonderful recipe. Made several times. A must on cold days. I fry the onions low and slow in a cast iron frying pan.

  22. Just confirming…. After you caramelize the onions for 8 hours in the slow cooker overnight then I add all the other ingredients, do I still cook for another 8 -10 hrs?

    • If you caramelize the onions overnight in the slow cooker and then add the other ingredients, you would then cook the soup another 8 hours before serving.

  23. Love your recipes! I would love to see a recipe for Chicken Tortilla Soup.

    • I made this recipe last night. Made enough that I could share it with ailing friends. We ALL loved it. I caramelized my onions on the stove pretty easily and let the broth and all cook for about 4 hours. I will make this again and again and again. Awesomeness!

  24. I carmelized my onions in the slow cooker the night before. Just turn it on before you go to bed (or sooner if you have to be at work in the morning). Add the rest of the ingredients and your good to go. You can always turn your slow cooker on warm if you’re not ready to put it in the oven yet. Waking up to the smell of carmelized onions had my mouth watering for dinner all day! Served this with Quiche and a salad

  25. Hello, I noticed in the carmalized onion recipe you called for 3lbs, but in the recipe for the soup you said 3 large onions. Is it really only 3 onions if you do the stove top carmalizing?

    • That’s correct, you need to have quite a few onions in the slow cooker so they caramelize properly. You will only need about half of them for this recipe.

  26. Sounds delicious. Any tips for cooking on stove top instead of crock pot? Thanks

  27. I made this today!! Souper good! I made it exactly how it was written. I give it an 8 out of 10. Next time I will add a little more splash of cooking Sherry for richness and I will cut up 6 onions. 3 Just was not enough for me. I’m so happy with this recipe and so grateful you posted this!! Bon Appetite!!

    • I am so glad you liked it Mel! I like the idea of a little more sherry. I will have to try that next time I make it!

  28. I add 1/3 cup of good red wine. Love this recipie. Exactly what I have ever been looking for.

  29. Hi Holly,
    I’m making this soup as I type. I’m using the crockpot method to caramelize the onions and noticed that there is no mention of the brown sugar from the original ingredient list, but there is an addition of salt. When I add the rest of the ingredients in the morning do I add the brown sugar then out just omit it altogether?
    Thanks, Sandra

    • Sorry for the confusion Sandra, the brown sugar helps the onions in the pan to caramelize a little bit quicker. I’ve found making them in the slow cooker, you don’t need the extra sugar. I’ve updated the post.

  30. Hello Holly, thank you for this article.

    Recipes make life easy and when resources like this are available, it just make healthy eating inviting.

  31. Sensational meals, that aren’t expensive or hard to prepare. We will try one tonite. Thanx for these great recipes.

  32. Just a suggestion for anyone who doesn’t have oven proof bowls. When you put you bread in the oven to dry/toast, when it’s the way you want it, simply top the bread with your cheese(s) and broil til browned and melted, then using a spatula move your bread onto the soup in your regular bowls.

    You can also make a confining ring from an old but cleaned can or other metal bottomless ring of any shape so the cheese doesn’t spread out too far, if that’s a problem for you. This also works with croutons, homemade or store bought!

    I hope this idea is helpful to someone since some of us don’t have the space or money for special oven proof bowls, or if you aren’t sure if yours IS oven proof!.

  33. I got Pastora medium dry sherry. Is this okay?

  34. Made tonight & it was very good! Thank you! Just took longer then recipe said to caramelize onions. I added more garlic cloves, one extra onion & used Gruyere & Swiss cheese! 

  35. I made this recently and it was SO easy and delish! I ended up buying jarlesburg cheese instead of gruyere cheese bc it was cheaper. I will make this again for sure! 

  36. This recie sounds great. BUT we don’t eat red meat. Can I substitute chicken bone broth ? Thanks

    • I have only tried this as written. If you try making the recipe with chicken broth, please let us know how it works out for you!

  37. Made this soup today.  Fantastic.  It made 8 servings, so we will freeze 4.  Very tasty.

    Rating: 5
  38. I used up the last of my red onions from this summer’s garden and made the recipe plus about a half amount more. I pre-caramelized the onions as you recommended and added them to the ingredients already warming in the crockpot. I recommend revving up the broiler before you ladle the soup into bowls, already on a sheet pain, and assemble the tops.
    The soup tasted like I had slaved all day but was incredibly easy to make. SO yummy on this snowy day!

    Rating: 5
  39. Hi Holly
    I am making your french onion soup for dinner today….not going to change anything except going to use 1/3 cup of white wine instead of sherry. I will let you know how I did..thanks Theresa

  40. YUMMY!!! Love onion soup and this recipe is the best,

    Rating: 5
  41. What are your suggestions for reheating this soup?

  42. I used 3lb of onions and carmelized them in the slow cooker overnight. My slow cooker only took 8 hours to get them translucent and golden. I used salted butter and did not use salt. Cooking sherry works very well.
    Delucious. Kathleen R. Calgary, Alberta

  43. I used salted butter and ommitted salt. Took 8 hours in my slow cooker to get onions translucent and golden. I use cooking sherry. Delicious. Kathleen R. Calgary Akberta

    Rating: 5
  44. I’m a french onion soup addict and a bit of a snob to boot. This is the best onion soup EVER! I caramelized the onions in the slow cooker and used all of them in the soup. Totally awesome!

  45. Made your soup with red onions and cooking sherry which has salt in it, then used the low sodium beef broth. Fantastico! Will be making it again this winter. Thank you for sharing.

  46. This is soooooo good. I do up a large slow cooker FULL of onions then freeze half to make it again in a couple of weeks,

    Rating: 5
  47. This was my first time making French Onion Soup and I am extremely pleased! Even my husband had a second bowl and he’s not had French Onion Soup before. I could not find Emmental cheese (not even sure what it is) but it tastes great without it. The ingredients blended well and the flavor rivals restaurant soups. Definitely a winner for a cool 20° night on Texas…or anywhere!

    Rating: 5
  48. Thanks for posting this recipe. I made it today, and it was delicious!

    Rating: 5
  49. Hi Holly,
    I love French Onion soup so I’m trying your recipe in the crockpot today. I just have a question. When I cook the onions on the stovetop with the butter and brown sugar, do I add the juice that was created from the butter and brown sugar to the crockpot with the onions ? 

    Rating: 5
  50. Hi! I soooo love this! Made this last night only thing I did different because I told my kids it’s onion soup they went blaa was I chopped up 3 lb of chicken thighs and put it in with the onions and the rest of they ingredients ! It came out so hearty and heavily! !! The family wants me to make this more!!! For the people who were worried about the Sherry how about alcohol content I bought cooking Sherry at the supermarket for $3 it does at such flavor!!! for the cheese I used freshly grated three cheese blend from my supermarket it had parmesan Asiago and Romano. I had the soup and soup Crocks put the bread in in the cheese on top and had them broiled in the oven till the cheese was brown and crispy! I highly recommend this recipe

    Rating: 5
  51. Wow Holly, thank you for writing this crock pot recipe. I actually don’t like onions in food and was recently convinced of its goodness. I’m traveling right now so I can’t try this out. Will be sharing with my friends, thanks.

  52. are yellow onions the same as white onion? can’t wait to make this!!!

    • White and yellow onions are a little different. White onions tend to have a sweeter flavor than yellow onions. They are often used interchangeably in recipes.

  53. FANTASTIC!!!

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