Description

This French Onion Mac and Cheese recipe combines the rich, caramelized flavors of slow-cooked sweet onions with creamy gruyere and parmesan cheeses, creating a decadent twist on the classic comfort food. The pasta is enveloped in a luscious cheese sauce with a nutty roux base and topped with seasoned bread crumbs for a crunchy finish, then baked until golden and bubbly. A sprinkle of fresh thyme adds a fragrant touch, making this dish perfect for cozy gatherings or special dinners.

Ingredients

Scale

Onion Base

3 tablespoons olive oil
4 large sweet onions, thinly sliced
Kosher salt and pepper, to taste

Pasta

1 pound short cut pasta, cooked according to package directions

Cheese Sauce

3 tablespoons unsalted butter
¼ cup all-purpose flour
2 ½ cups milk
¼ teaspoon freshly ground nutmeg
12 ounces gruyere cheese, freshly grated
4 ounces parmesan cheese, freshly grated

Topping

⅓ cup seasoned bread crumbs
Fresh thyme, for serving

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Instructions

Cook the onions: Heat the olive oil in a large oven-safe skillet over medium heat. Add the thinly sliced onions and a generous pinch of salt. Stir frequently and cook until the onions soften, about 10 to 15 minutes.
Caramelize the onions: Reduce heat to low or medium-low. Continue cooking the onions, stirring often, for 60 to 90 minutes until they become golden and caramelized. If onions begin to stick or burn, lower the heat or add a splash of water to prevent drying out.
Preheat oven and prepare pasta: Preheat your oven to 375°F (190°C). Meanwhile, boil the pasta according to package instructions until al dente, then drain and set aside.
Set aside caramelized onions: When onions are golden and caramelized, transfer most of them to a plate, reserving some for layering on top of the dish.
Make the roux and sauce: Add butter to the skillet used for onions and melt over medium heat. Stir in the flour and cook for 2 to 3 minutes until it turns golden and smells nutty. Gradually whisk in the milk, stirring constantly to prevent lumps. Continue stirring until the sauce thickens. Add the freshly ground nutmeg.
Add cheese and combine: Stir in almost all of the grated gruyere and parmesan cheeses, reserving some for topping. Once melted, fold in three-quarters of the caramelized onions and the cooked pasta. Toss everything gently to combine well.
Top and bake: Spread the mac and cheese mixture evenly in the skillet. Top with the remaining cheese and reserved caramelized onions. Sprinkle the seasoned bread crumbs evenly over the top. Transfer the skillet to the oven and bake for 25 to 30 minutes until the top is golden and bubbly.
Serve: Remove from the oven and garnish with fresh thyme leaves. Serve hot and enjoy the rich flavors and comforting textures.

Notes

To speed up caramelization, add 1 teaspoon of sugar, honey, or maple syrup to the onions while cooking, but stir often to avoid burning.
Be sure to use an oven-safe skillet to avoid transferring the mac and cheese to another dish before baking.
Gruyere can be substituted with Emmental or a good quality Swiss cheese for similar flavor.
Seasoned bread crumbs add extra flavor and crunch; plain bread crumbs can be used but consider adding herbs or garlic powder.
Leftovers can be refrigerated for up to 3 days and reheated in the oven for best texture.