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!
© SpendWithPennies.com
Crockpot French Onion Soup
French Onion Soup is one of my husband’s all-time favorites. It’s the perfect meal for any soup lover!
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 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!
How 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 make 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!
More Crockpot Soups You’ll Love
- Slow Cooker Chicken Pot Pie Soup – Comforting and creamy.
- Crock Pot Cabbage Roll Soup
- Slow Cooker Chicken Enchilada Soup
- Crockpot Chicken Noodle Soup – Great for leftovers!
- Slow Cooker Cajun Bean Turkey Soup Recipe
- Easy Crock Pot Ham and Potato Soup – Favorite recipe!
Equipment
Ingredients
- 3 large white onions sliced
- 3 tablespoons butter
- 64 ounces beef broth I use reduced sodium
- 1 tablespoon Worcestershire sauce
- 1 clove garlic minced
- ⅓ cup dry sherry
- 4 sprigs fresh thyme or 1 teaspoon dried thyme
- 1 bay Leaf
- 8 slices French bread * stale or dry is best
- ¾ cup shredded Gruyere cheese
- ½ cup shredded Emmental cheese
- 6 tablespoons shredded Parmesan cheese
Instructions
- In a large non-stick pan, cook onions, and butter over medium-low heat until golden and caramelized. (About 20 minutes).
- Once golden, add to the slow cooker along with the remaining ingredients except for bread and cheese.
- Cook on low for 6 to 8 hours.
- Remove and discard bay leaf and ladle the soup into bowls. Top with dry bread slices and cheeses. Broil 2 to 3 minutes or until cheese is melted and browned.
Video
Notes
Nutrition Information
Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.
Course Dinner, Lunch, Soup
Cuisine American, French© SpendWithPennies.com. Content and photographs are copyright protected. Sharing of this recipe is both encouraged and appreciated. Copying and/or pasting full recipes to any social media is strictly prohibited. Please view my photo use policy here.
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What are your suggestions for reheating this soup?
We reheat it in the microwave or on the stovetop and then ladle it into bowls and add the bread and cheese. Enjoy!
YUMMY!!! Love onion soup and this recipe is the best,
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
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!
I’m so glad you loved it! I bet it was even better with onions from your garden! :)
Made this soup today. Fantastic. It made 8 servings, so we will freeze 4. Very tasty.
I am so glad you enjoyed this recipe Sandi!
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!
You could probably use vegetable broth.
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!
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!
I got Pastora medium dry sherry. Is this okay?
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!.
Great idea Sandra, thank you for sharing!
Sensational meals, that aren’t expensive or hard to prepare. We will try one tonite. Thanx for these great recipes.
Hello Holly, thank you for this article.
Recipes make life easy and when resources like this are available, it just make healthy eating inviting.
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.
I add 1/3 cup of good red wine. Love this recipie. Exactly what I have ever been looking for.
Sounds like an amazing addition to this soup!
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!
Sounds delicious. Any tips for cooking on stove top instead of crock pot? Thanks
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.
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
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!
You’ll find chicken tortilla soup here!
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.