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 on the recipe card below.
- 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 the tip to the 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 cleanup easy.
- 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
Nutrition
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Neely Moldovan
Oh I usually do roasted onions with other veggies but this sounds delish!
Ej Requina
A perfect side dish for steaks! Definitely be preparing this on my next family gathering I am sure this is going to be a hit!
Rosey
I’ve never roasted nor heard of someone roasting just an onion, but it sounds and looks fabulous. Pinning it for when I feel adventurous.
Ivan Carlo Jose
We love to make roasted onions at home. The caramelized edges taste lovely.
Claudia
I love that these simple oven-roasted onions are tender, mellow, and delicious. It doesn’t require so much peeling!
Ntensibe Edgar
You spoke of the pork tenderloin and I remembered a meal I had a few weeks ago! It was the roasted onion that made it so good.
Bryan
I do love onions. I know some people don’t like them at all, but I enjoy them. And the roasted version is often less hot and more palatable, sometimes making them acceptable to non- onion lovers.
Beth Pierce
Very true!
Krystle
I can’t believe I’ve never roasted onions before. These are such a treat
Stephanie
Such a simple but great recipe! I had made roasted vegetables before, but hadn’t thought of trying it with whole onions. My family loves sweet onions!
Christine
Yum! I happen to love onions so this looks so good. I can’t wait to try this recipe. Thank you!