Creamy Baked Onions with Asiago Cheese
Creamy Baked Onions with Asiago Cheese is the cozy, unexpected side dish you didn’t know you needed. Tender, caramelized onion rounds are blanketed in a silky Dijon cream sauce and topped with nutty Asiago cheese, then baked until bubbly and golden.
It’s elegant enough for holiday dinners and easy enough for weeknight comfort food.
Why You’ll Love This Recipe
Simple ingredients, big flavor – Onions transform into something luxurious with just a few pantry staples.
Creamy, cheesy, and herbaceous – Every bite melts in your mouth with a balance of richness and warmth.
Versatile side dish – Pairs beautifully with roasts, grilled meats, or vegetarian mains.
Unexpected yet familiar – A unique alternative to traditional gratins or casseroles that still feels comforting and classic.
Key Ingredients
Yellow Onions – When roasted, they develop sweet, caramelized edges and a tender bite.
Heavy Cream – Provides richness and creates a smooth, indulgent sauce.
Asiago Cheese – A sharp, nutty cheese that adds depth and savory flavor.
Dijon Mustard – Adds a subtle tang that balances the creamy richness.
Fresh Thyme – Infuses the dish with earthy, aromatic notes.
Creamy Baked Onions with Asiago Cheese
Ingredients:
4 large yellow onions, sliced into ¼-inch rounds
Olive oil (for drizzling)
½ tsp chopped fresh thyme
Salt and black pepper (to taste)
1 cup heavy cream
2 tsp Dijon mustard
½ cup grated Asiago cheese
Instructions
Roast the Onions:
Preheat your oven to 450°F (230°C). Lightly grease a baking dish, then arrange the onion slices in a single, even layer.
Drizzle the onions with olive oil and sprinkle with chopped thyme, salt, and pepper. Roast for about 20 minutes, until the edges are golden and the onions begin to caramelize.
Make the Creamy Sauce:
While the onions are in the oven, warm the heavy cream in a small saucepan over medium heat.
Once it begins to simmer, stir in the Dijon mustard and half of the Asiago cheese. Stir until smooth and melted.
Finish Baking:
Remove the roasted onions from the oven and pour the cream sauce evenly over the top. Sprinkle with the remaining Asiago cheese. Cover the dish with foil and return it to the oven.
Bake for another 20 minutes, until the onions are soft and the sauce is bubbling. Uncover for the last few minutes if you want the cheese to brown slightly on top.
Tips and Shortcuts
Slice onions evenly for uniform roasting and texture.
Use a mandoline for fast, even slicing.
Pre-grated cheese is convenient, but freshly grated Asiago melts better and tastes more vibrant.
Roast the onions ahead of time and refrigerate, then add sauce and bake when ready to serve.
Swap cream for half-and-half to lighten it slightly (though it won’t be quite as rich).
Nutrition Information
YIELDS: 6 | SERVING SIZE: 1
Calories: ~210 | Fat: 17g | Saturated Fat: 10g | Carbohydrates: 11g | Fiber: 2g | Protein: 5g | Sugar: 5g | Sodium: ~260mg
Kitchen Equipment Needed
Sharp knife or mandoline
Cutting board
Medium baking dish
Small saucepan
Mixing spoon or whisk
Foil (for covering during baking)
Recipe Swaps and Variations
Cheese Swap: Try Gruyère, sharp white cheddar, or Parmesan in place of Asiago.
Add crunch: Top with crispy breadcrumbs or crushed crackers during the last 10 minutes of baking.
Add veggies: Layer in thin-sliced mushrooms, leeks, or fennel.
Make it smoky: Add a pinch of smoked paprika or use smoked cheese.
Vegan-friendly: Use plant-based cream and cheese alternatives, and skip the Dijon or choose an egg-free version.
How to Store Leftovers
Refrigerator: Store in an airtight container for up to 3–4 days.
Reheat: Warm in the oven at 350°F or microwave in short intervals until heated through.
Freezer: Not ideal, as cream-based sauces may separate—best enjoyed fresh or refrigerated.
Food and Drink Pairings
Best served with:
Roasted chicken, pork tenderloin, or beef ribeye
Herb-stuffed mushrooms or grilled portobellos
Buttery mashed potatoes or crusty bread
Drink ideas:
Dry white wine (Chardonnay, Pinot Grigio)
Sparkling cider or herbal iced tea
A crisp lager or light saison-style beer
Frequently Asked Questions:
Can I use red or sweet onions instead?
Yes! Red onions will give a slightly more intense flavor, and sweet onions will be even milder and sweeter after roasting.
What can I use instead of Asiago?
Parmesan, Gruyère, or Romano cheese are all great substitutes that melt well and have bold flavors.
Is Dijon mustard necessary?
It adds a tangy balance to the richness, but you can reduce or skip it for a milder taste.
Can I make this dish ahead of time?
Yes! Roast the onions and make the sauce, then assemble and refrigerate.
Just bake before serving.
Can I make this dish lighter?
Swap the heavy cream with half-and-half or a mixture of milk and Greek yogurt—but the texture will be slightly less rich.
How thin should the onion slices be?
About ¼ inch thick.
This helps them roast evenly without becoming too soft or too crisp.
Do I need to separate the onion rings?
No, keeping the slices intact gives the dish a layered, gratin-style presentation.
You can separate them if preferred.
Should I cover the dish while baking?
Yes—for the second baking phase.
Covering helps the sauce stay creamy and the onions stay tender.
Remove foil at the end for browning.
My sauce is too thick—what can I do?
Add a splash of milk or cream and stir to loosen before pouring over the onions.
Can I double this recipe for a crowd?
Absolutely! Use a larger casserole dish and adjust baking time slightly.
It’s perfect for potlucks or holiday meals.