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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Elizabeth
WOW!! What a great side and so easy to make. Thanks for this amazing recipe.
Beth Pierce
You are most welcome, Elizabeth!
Chikumo Fiseko
I will try to make this too! Good thing I was able to visit your blog. Pretty interesting recipe! Thank you for sharing. Hopefully, I can make this successfully.
Beth Pierce
I am sure you will do just fine. The recipe is fairly easy.
Mila R
OMG, this was great! They are delicious! My whole family loved them so much!
Kat
This dish was so easy to make and so tasty. Thank you for the recipe.
Irrena
If you have fresh herbs like rosemary it really does this recipe justicce! thanks for sharing
Beth Pierce
My please Irrena! I love fresh rosemary!
Rose Ann Sales
Wow! These were absolutely delicious and tasty! Such an easy recipe and they are a great side dish for so many things.
Neely Moldovan
Oh yum! I love roasted onions. Such a great thing to add to different meals!
Alita
Roasted onions are the best and an ultimate favorite at home. I make them repeatedly and the kids love them.
Gervin Khan
Wow! This onion dish was absolutely delicious. It was perfectly roasted and the texture was spot on. We had them with some grilled steak and we loved it.
Tweenselmom
Onions are my fave food toppings and roasted onions are the best. Thanks for sharing the recipe. It was easy and yummy!
Christine
Yum! I love onions. This is such a great side dish. The whole family really enjoyed it.
Tameka H
This will go perfectly with my roasted pork! Thanks for this!
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.