Whole Roasted Onions Recipe – good buttery whole roasted onions baked to perfection – solid as a side dish! This is the solid gorgeous – but crazy easy – side dish for a holiday dinner or even Sunday supper – and it makes the whole house smell good.

These onions roast to soft, buttery perfection with a couple herbs and spices – and are fabulous paired with pork tenderloin steaks turkey chicken thighsor any hearty main dish you love! We hope you love this recipe as much as we do!

At Avdaye, we add lots of tips in all of our recipes – because we are a home cook without any formal training, and we find we are more confident making dishes when we understand why it works, and what each ingredient means to the flavor of a recipe. Our goal is for even the most beginner home cook to feel empowered in the kitchen.

How To Roast Whole Onions

First assemble the following ingredients:

Yellow onions (6) – Whole yellow onions become meltingly tender and caramel-sweet when roasted, developing deep golden edges and a rich, savory aroma.
Butter (6 tablespoons) – Butter adds luscious richness and helps the onions brown beautifully, creating a silky, flavorful glaze as it melts.
Italian herb seasonings (1 tsp) – Italian herbs infuse the onions with earthy, aromatic notes of oregano, basil, and thyme that enhance their natural sweetness.
Fresh rosemary or thyme (2-3 sprigs) – Fresh rosemary or thyme adds fragrant, woodsy depth and a subtle herbal brightness to each roasted bite.
Salt and pepper (to taste) – Salt and pepper balance the sweetness of the onions and highlight the butter and herbs with simple, classic seasoning.

Assemble

Assemble the ingredients. Cut the top and bottom off onion to make a flat surface, leaving peel on.

Season

Place into baking dish, either lined with foil or prepped with nonstick cooking spray. Sprinkle with salt, pepper, and herbs.

Butter it Up

Top with a pat of butter on each onion.

Bake

Bake 60-90 minutes at 350 degrees, until onions are browned, soft, and fragrant. When serving, remove peel.

Kitchen notes

Bake Completely –Baked onions are done when they are browned and soft, which can take anywhere from 60-100 minutes.

Don't rush your onions – make them ahead of time and reheat if you're worried about timing for an event, as the flavor can't be rushed for this recipe.

Choose uniform onions – Pick onions that are roughly the same size so they roast evenly and finish cooking at the same time.

Leave the root end intact – This helps hold the onion layers together as they soften and prevents them from falling apart.

Use a baking dish with high sides – Onions release juices as they roast; a dish with sides keeps them moist and helps caramelize the edges instead of drying out.

Deglaze the pan for extra flavor – After roasting, pour a splash of broth, wine, or balsamic vinegar into the dish and swirl to pick up the golden bits for a quick drizzle sauce.

Try different onion varieties – Mix yellow, red, and sweet onions for color and subtle flavor variations.

A few answers

When are whole roasted onions done?

Baked onions are done when they are browned and soft, which can take anywhere from 60-100 minutes.
Don't rush your onions – make them ahead of time and reheat if you're worried about timing for an event, as the flavor can't be rushed for this recipe.

Do you roast onion in the skin?

We roast onion in the skin for the best flavor – discard when serving.

Are whole roasted onions vegan?

This recipe isn't expressly vegan, as we're using butter.
Swap the butter for equal amounts of olive oil drizzled over the onions to make it vegan!

How long can whole roasted onions be kept?

This recipe can be stored in the refrigerator in an airtight container for up to five days.

Other Easy Side Dishes You'll Love

If you're looking for other dishes to pair alongside a pork tenderloin London broil turkey breast lobster tailsor even cauliflower steaks – please check out some of our favorite side dishes below:

You can find our entire side dish recipe index here.

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Ingredients

6 yellow onions
6 tablespoons butter, cut into 6 pats for each onion (use olive oil for vegan)
1 tsp italian herb seasonings
2-3 sprigs fresh rosemary or thyme
salt and pepper, to taste

Method

Preheat oven to 350 degrees.
Cut the top and bottom off onion to make a flat surface, leaving peel on.
Place into baking dish, either lined with foil or prepped with nonstick cooking spray.
Sprinkle with salt, pepper, and herbs.
Top with a pat of butter.
Bake 60-90 minutes at 350 degrees, until onions are browned, soft, and fragrant.
When serving, remove peel.