These easy roasted onions combine sweet onions with olive oil, butter, kosher salt, fresh ground black pepper, and fresh thyme and rosemary into a flavor-packed aromatic side dish. It is a must-try for all onion lovers and a regular roasted veggie at our house.
With just a handful of simple ingredients and a few minutes of preparation, this tasty vegetable recipe is a must-have for every good cook. I love serving this side with grilled steak and roasted chicken, but endless possibilities exist.
Ingredient Notes and Substitutions
See the complete list of ingredients below on the recipe card.
- Onions: preferably sweet yellow onions or Vidalia onions.
- Seasonings: salt and freshly ground black pepper
- Herbs: fresh rosemary, thyme, parsley
How to Roast Onions
This is just the nutshell version. See the recipe card below for complete directions.
Cut the onions in half from tip to root, then remove the outer dried layers. Arrange them in a single layer, cut side up, on a rimmed baking sheet covered with parchment paper. Drizzle with olive oil and top each half with a pat of butter.
Sprinkle generously with kosher salt and fresh ground black pepper. Top with fresh thyme leaves and chopped fresh rosemary. Roast for 35-45 minutes or until golden brown. Sprinkle with more fresh thyme and rosemary.
Preparation Tips
- This recipe works with any number of fresh herbs. We love adding thyme, rosemary, Italian parsley, or whole cloves of garlic to the baking sheet.
- Parchment paper helps the onions brown better and cook more evenly. It is usually rated up to 420 degrees Fahrenheit but check your box. As a bonus, it makes for easy clean-up.
- These sweet treats are best served promptly but can easily be heated again in the hot oven for about 5 minutes.
Serving Suggestions
I like to serve these onions with New York strip steak, air fryer salmon, or beef roast. For something different, try a big bowl of hearty soup like minestrone or meatball soup.
Roasted Onions
Ingredients
- 4 medium sweet yellow onions sliced in half from root to tip
- 3 tablespoons olive oil
- 2 tablespoons butter
- kosher salt
- fresh ground black pepper
- fresh rosemary chopped
- fresh thyme leaves
Instructions
- Preheat the oven to 400 degrees. Cover a small baking sheet with parchment paper.
- Cut the onions in half from tip to root then remove the outer dried layers. Lay them cut side up on the prepared baking sheet in a single layer.
- Drizzle with olive oil and top each half with a pat of butter. Sprinkle generously with kosher salt and fresh ground black pepper. Top with fresh thyme leaves and chopped fresh rosemary.
- Roast for 40-45 minutes or until golden brown and tender. Sprinkle with more fresh thyme and rosemary. For best results, serve promptly.
Notes
- This recipe works with any number of fresh herbs. We love adding thyme, rosemary, Italian parsley, or whole cloves of garlic to the baking sheet.
- Parchment paper helps the onions brown better and cook more evenly. It is usually rated up to 420 degrees Fahrenheit but check your box. As a bonus, it makes for easy clean-up.
- These sweet treats are best served promptly but can easily be heated again in the hot oven for about 5 minutes.
- Store leftovers in an airtight container for up to 3 days.
Nutrition
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Michelle
Served these roasted onions as a side for Thanksgiving and everyone raved about them! Definitely recommend.
Beth Pierce
Thank you, Michelle!
Catie S
Wow, I never thought roasted onions could be this good! The caramelized edges and rich flavor were incredible, and they made the perfect side dish for our steak dinner.
Beth Pierce
Thanks, Catie! So glad that you enjoyed them!
Kat
This is so simple and delicious! The perfect side dish or topping for burgers, steaks, or salads. Easy to make and full of flavor!
Beth Pierce
Thank you, Kat! I am so glad that you liked it!
Cristol
These onions are amazing! Roasting them with thyme and rosemary brings out such incredible flavor. Who knew a humble onion could taste so good? The herbs really take this simple side dish to the next level! Thanks for the great recipe.
Tayler
I made these onions as a side with dinner last night and they were delicious! Already can’t wait to make them again!
Holley
Sooooo delicious! I love these onions with my steak bites!
Justine
I don’t often think of onions as being a dish on their own, but they’re really great – and this is a fantastic way to showcase them!
Beth Pierce
Thank you, Justine!
paula
Loved this roasted onion recipe. It went great with dinner last night!