If you’ve never had Roasted Onions, they’re a delicious side dish and have so much flavor!

In this recipe, the onions become sweet and mellow with caramelized bits as each piece softens. and softens each piece, making these onions both sweet and savory. These are perfect to enjoy on their own or to add to so many other recipes!

serving plate with Roasted Onions and thyme

Sweet, Savory, & So Easy!

  • Simple and inexpensive, this side goes with almost any meat.
  • Prep is about 5 minutes. Simply slice, season and bake.
  • Part of the allium family, and just like roasted garlic, when onions are oven roasted they become mellow and sweet.
  • Add leftovers to soup, stew or my favorite, add it to gravy!

ingredients for Roasted Onions with labels


ONIONS All onions are readily available and affordable. Yellow onions are most popular in many recipes and are perfect for roasting. But we really love sweet white onions or Walla Wallas. Of course, any onion will work.

As a garnish with holiday lamb, ham, or turkey, try using pearl onions and cippolini onions. These can be baked whole.

SEASONINGS Rosemary and thyme are excellent sprigs of herbs to add to the dish as the onions roast. Add them whole across the tops of the onions for a delicate flavor or chop them finely and sprinkle over top for more herb flavor.

onions slices on a wooden board and in a dish for Roasted Onions

How to Roast Onions

Roast these in the oven until they are crisp, golden, and irresistible.

  1. Prepare the butter mixture. Slice the onions & place them in a casserole dish.
  2. Brush the onions with the butter mixture. Add water, salt, & pepper.
  3. Roast (as per the recipe below).

Depending on the preference, the material of the baking dish, and the type of onion, cooking can vary. I prefer a ceramic or glass dish and love the little crispy edges. Check the onions early and roast to your preference.

Roasted Onions in a baking dish with thyme

Best Way to Use Roasted Onions

I love to eat them warm out of the pan just as is.

There are so many ways other ways to use these roasted onions!


Keep leftover roasted onions in a covered container in the refrigerator for up to 5 days. Reheat in the microwave or enjoy them cold in a burger or wrap. Leftovers can be added to different soups like Cream of Onion Soup, Slow Cooker French Onion Soup, and Homemade French Onion Soup. These would go great with a thick piece of homemade bread.

Our Fave Roasted Veggies

Did your family love these Roasted Onions? Leave us a comment and a rating below! 

Roasted Onions on a serving plate with thyme as garnish
5 from 26 votes↑ Click stars to rate now!
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Roasted Onions

Roasted onions are so versatile and add flavor to so many dishes. Balsamic vinegar, butter, and some heat from the oven will make these onions crispy and caramelized. 
Prep Time 10 minutes
Cook Time 50 minutes
Total Time 1 hour
Servings 4


  • 2 large sweet onions 1 ½ -2 pounds
  • 2 tablespoons melted butter
  • 1 teaspoon balsamic vinegar
  • 3 tablespoons water or broth
  • teaspoon kosher salt or to taste
  • teaspoon freshly ground black pepper


  • Preheat the oven to 400°F.
  • Whisk melted butter and balsamic vinegar.
  • Peel the onions and cut into ½" slices, do not separate the rings.
  • Place the onions in a greased 9x13 baking dish and brush with the butter mixture. It's ok if they overlap a little bit.
  • Pour the water into the casserole dish.
  • Season with salt and pepper and roast 40-50 minutes or until golden and tender.


Depending on the preference, the material of the baking dish, and the type of onion, cooking can vary. I prefer a ceramic or glass dish and love the little crispy edges.
Check the onions early and roast to your preference.
Leftover roasted onions can be kept in the fridge in a covered container for up to 5 days. They make a great addition to gravy, soup or stew.
5 from 26 votes

Nutrition Information

Calories: 104 | Carbohydrates: 13g | Protein: 1g | Fat: 6g | Saturated Fat: 4g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 1g | Trans Fat: 1g | Cholesterol: 15mg | Sodium: 132mg | Potassium: 201mg | Fiber: 2g | Sugar: 9g | Vitamin A: 177IU | Vitamin C: 8mg | Calcium: 36mg | Iron: 1mg

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

Course Side Dish
Cuisine American
Roasted Onions in a dish with text
Roasted Onions in a serving dish with a title
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Roasted Onions in a baking dish and on a plate with writing



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About the author

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!
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Recipe Rating


  1. Making today. Using up leftover ribeye steak and will roast portobello mushrooms to with and some blue cheese to bring it all together.5 stars

  2. The Roasted Onions will be made today. i cant wait to try them as i have been looking for just the right recipe and i believe i have found it. i just LOVE
    onions however they are done.5 stars

  3. OMG!! These were the best and the best part is that they are nearly as easy to fix as microwave popcorn, except they take about 40 minutes to bake. Since there is only the one of me, I made roughly 1/3 the recipe, but made about 1/2 the butter mixture to slather on the top. I did go crazy and used all but one of the alternate spices, but they were absolutely delicious. I couldn’t ask for a better pairing with my steak. I would recommend using about 1/8” to 1/4” of water to prevent burning. If I had left them in the oven another 10 minutes, they probably would have gotten a bit too crispy. Also recommend using a spatula to get them out because the rings will separate if you are not careful.5 stars

  4. This is one of those dishes that will have a permanent place in my recipe box. It was so easy, and so good, that I had to fight with myself to keep from eating ALL of them. I am counting calories so again; this was helpful in finding a delicious side dish to go with my meal. I couldn’t be happier. Now, if I can just leave them alone till lunch time…sigh.5 stars