Introduction

French Onion Mac and Cheese is a comforting twist on a classic favorite, combining rich caramelized onions with creamy, cheesy pasta. This dish offers deep, savory flavors perfect for cozy dinners or special occasions.

This close-up image shows a baked pasta dish in a white enameled cast iron pot with a handle. The dish has multiple layers, starting with soft, creamy macaroni pasta mixed with melted cheese underneath. On top, there is a thick, golden-brown crust of baked cheese and crispy breadcrumb bits. Scattered small green herb sprigs are placed on the top as garnish. The edges of the pot have browned, bubbling cheese sauce that looks rich and gooey, and a silver spoon rests inside the pot, scooping some of the pasta. The background is a white marbled surface. photo taken with an iphone --ar 4:5 --v 7

Ingredients

3 tablespoons olive oil
4 large sweet onions, thinly sliced
Kosher salt and pepper, to taste
1 pound short cut pasta, cooked
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
⅓ cup seasoned bread crumbs
Fresh thyme, for serving

Instructions

Step 1: Heat the olive oil in a large oven-safe skillet over medium heat. Add the sliced onions with a generous pinch of kosher salt and cook, stirring often, until they soften, about 10 to 15 minutes.
Step 2: Reduce the heat to low or medium-low. Continue cooking the onions, stirring frequently, for 60 to 90 minutes until they turn golden and caramelized. If onions begin to burn, lower the heat or add a few splashes of water to keep them moist.
Step 3: Preheat the oven to 375°F (190°C). Meanwhile, boil the pasta according to package directions until al dente, then drain.
Step 4: Transfer the caramelized onions to a plate. (If you need to speed up caramelization, add 1 teaspoon of sugar, honey, or maple syrup during cooking and stir often to prevent burning.)
Step 5: Add the butter to the skillet. Once melted, whisk in the flour to make a roux. Cook for 2 to 3 minutes until golden and fragrant. Slowly pour in the milk while whisking constantly to avoid lumps. Stir in the nutmeg and cook until the sauce thickens.
Step 6: Stir in most of the Gruyere and Parmesan cheese until melted. Add in three-quarters of the caramelized onions, then toss in the cooked pasta. Mix thoroughly to combine all ingredients.
Step 7: Top the mac and cheese with the remaining cheese and caramelized onions. Sprinkle the seasoned bread crumbs evenly over the top. Bake for 25 to 30 minutes until the crust is golden and bubbly.
Step 8: Remove from the oven and garnish with fresh thyme before serving.

Tips & Variations

Use yellow or white onions if sweet onions are unavailable, though the flavor will be less sweet.
For a quicker version, add a teaspoon of sugar or honey while caramelizing onions to speed up the process.
Try using a mix of cheeses like sharp cheddar or fontina to vary the flavor.
Serve with a crisp green salad to balance the richness.

Storage

Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven at 350°F (175°C) until warmed through to maintain a crispy top. You can also microwave portions, though the topping may lose some crunch.

How to Serve

A white plate holds a serving of baked macaroni and cheese with a crispy, golden-brown top layer of melted cheese and breadcrumbs, showing some darker toasted spots. The macaroni underneath is coated in creamy, light yellow cheese sauce with slightly browned edges. Small green herb leaves are scattered on top and around the dish for garnish. A fork rests on the plate with some macaroni and cheese on it, and part of a white dish filled with more of the macaroni and cheese is visible at the plate's edge. The background is a white marbled texture. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use different pasta shapes for this recipe?

Yes, short cut pastas like elbow macaroni, shells, or cavatappi work well because they hold the cheese sauce nicely.

How do I know when the onions are properly caramelized?

The onions should be a rich golden brown color, soft, and sweet in flavor without any burnt bits. This process takes patience but develops the key flavor of the dish.