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Roasted Parmesan Creamed Onions

These easy Roasted Parmesan Creamed Onions will wow your family or dinner guests with very little effort on your part. Simply slice up some sweet onions, pop them in the oven to transform their flavor, then smother them in an utterly addictive Parmesan cream sauce. I’m telling you, pure magic happens when humble ingredients like onions, flour, milk, broth and cheese combine to create a side dish so decadent yet easy, it should be illegal!
As the onions roast, their natural sugars caramelize, intensifying their inherent sweetness tenfold. Each slice becomes meltingly tender, practically fusing with the rich and creamy Parmesan-laced sauce you’ll later pour over the top. The result? Sweet and savory perfection in every single bite!
You and your guests will devour these onions with reckless abandon, mopping up every last drop of that spectacular sauce. And did I mention that putting this side dish together takes a mere 10 minutes of prep? Yes, in just 50 minutes total, you can have a restaurant-worthy dish with very little hands-on effort!
Now, let’s talk about choosing the right onion. Yellow onions are the classic choice here, lending a mildly pungent flavor that balances beautifully with the sweet caramelization and savory Parmesan sauce. Their texture also holds up well to roasting without turning mushy. However, a sweet onion like Vidalia or Walla Walla can take this side to new heights of flavor. Just be careful not to roast them quite as long or they’ll lose their shape. No matter which you choose, this is one rich, addictive and extra easy recipe you’ll make again and again!

What type of onion works best?
Yellow, white, or red onions are all great choices. Yellow onions are the classic pick with the best balance of flavor and texture.

Can I use pre-sliced onions?
Absolutely! The prep will be even easier.

What does roasting do to the onions?
It caramelizes their natural sugars and transforms the texture from crisp to soft and jammy. Definitely key for flavor!

Why add flour to the sauce?
The flour thickens the cream and broth mixture into an ultra rich, decadent sauce that clings perfectly to every bite of onion.

What makes Parmesan the best finishing cheese?
Its savory, nutty flavor and salty punch cuts through the sweetness of the onions. As it melts, it takes the sauce over the top.

Should the onions be hot or room temp before saucing?
Let the just-roasted onions cool for 5 minutes before pouring over the hot cream sauce so they properly absorb it.

What can I add for crunch?
Toasted breadcrumbs, crumbled bacon, or chopped nuts would all provide a nice textural contrast!

Prep Time: 10 minutes
Cook Time: 40 minutes
Total Time: 50 minutes


  • 3 medium yellow onions, peeled and cut into 1/2-inch thick slices (about 3 cups)
  • 3 tablespoons unsalted butter, divided
  • 1/4 teaspoon salt
  • 1/8 teaspoon black pepper
  • 3 tablespoons all-purpose flour
  • 1 1/4 cups whole milk
  • 1/2 cup vegetable or chicken broth
  • 1/3 cup freshly grated Parmesan cheese
  • 2 tablespoons chopped fresh parsley


  1. Start by preheating your oven to 400°F to get it nice and hot for roasting. While the oven heats up, peel 3 medium yellow onions and carefully slice them into 1/2-inch thick rounds. You should end up with about 3 cups sliced onions. Place the onion slices in a large 9×13-inch baking dish.
  2. Add 2 tablespoons of unsalted butter to the dish and toss gently until the onion slices are thoroughly coated in melted butter. This helps them roast up caramelized and sweet later. Next, sprinkle on 1/4 teaspoon of salt and 1/8 teaspoon of black pepper over the buttered onions. Toss several times again until the seasonings evenly distribute over each piece.
  3. Put the baking dish with your seasoned onions into the hot 400°F oven. Let them roast undisturbed for the first 15 minutes. Then, open the oven, give the dish a careful stir so the onions roast evenly, and pop back in the oven for another 15-20 minutes. You want the onions deeply golden brown with caramelized edges by the time they come out.
  4. While your onions roast in those last 15 minutes, make your savory Parmesan cream sauce. Melt the remaining 1 tablespoon of butter in a medium saucepan over medium heat. Quickly whisk in 3 tablespoons of all-purpose flour which will thicken up our sauce beautifully. Cook the butter-flour mixture together for 1 minute, whisking constantly so it doesn’t burn.
  5. Next, slowly pour in 1 1/4 cups of whole milk along with 1/2 cup chicken or vegetable broth, while continuing to whisk vigorously. Bring this creamy mixture to a gentle simmer, then let it bubble away for 5-7 minutes, frequently whisking the entire time, until thickened to a rich, silky sauce consistency that coats the back of a spoon.
  6. Once your onions have achieved that deep golden color, remove them from the oven but DON’T shut off the heat yet. Give them just 5 minutes to cool slightly. Then pour your freshly made Parmesan sauce all over those sweet roasted onions. Gently toss using kitchen tongs or spatulas until each piece gets thoroughly coated in velvety, cheesy sauce. Mmmm!
  7. Quickly sprinkle on 1/3 cup freshly grated Parmesan cheese so it can melt into that hot sauce. Return the sauced onions back to the still-hot 400°F oven for exactly 5 more minutes. This gives the cheese time to melt into stringy, gooey deliciousness blanketing those onions.
  8. Finally, use oven mitts to carefully transfer your masterpiece side dish to a serving platter. Garnish with some chopped fresh parsley for color. Then dig your fork right into these creamy dreamy onions! The texture pairs so perfectly with the intermingling sweet and savory flavors in each decadent bite.

Cooking tips:

  • Use full-fat dairy products for ultimate richness.
  • For deeper flavor, sauté the onions before roasting.
  • Stir the cream sauce frequently as it simmers to prevent scorching.
  • Let the roasted onions cool slightly before topping with the hot sauce.
  • Grate the Parmesan fresh for tangy, nutty flavor.
  • Add toasted breadcrumbs or nuts for extra texture and crunch.

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