Introduction

French Onion Soup Mac & Cheese is a comforting twist on two classic dishes. It combines rich caramelized onions and a blend of melted cheeses with creamy pasta, topped with a crispy breadcrumb crust. This hearty casserole is perfect for cozy dinners.

A close-up view of a creamy macaroni and cheese dish in a white bowl, showing a thick layer of melted, golden-brown cheese on top with specks of black pepper and herbs. The macaroni noodles underneath are covered in gooey, stretchy cheese with a rich, smooth texture, some parts toasted to a light crisp on the surface. A spoon lifts a portion, pulling strands of melted cheese and small macaroni curved shapes, highlighting the warm and cheesy feel. The background features a softly blurred white marbled texture. photo taken with an iphone --ar 4:5 --v 7

Ingredients

12 ounces elbow macaroni
3 large yellow onions, thinly sliced
2 tablespoons olive oil
3 tablespoons butter
2 cloves garlic, minced
3 tablespoons flour
2 cups vegetable broth
2 cups whole milk
1/2 cup heavy cream
2 cups shredded Gruyère cheese
1 cup shredded sharp cheddar cheese
1 cup shredded mozzarella cheese
1 teaspoon salt
1/2 teaspoon black pepper
1 teaspoon fresh thyme (or 1/2 teaspoon dried)
1 cup breadcrumbs
1/2 cup grated Parmesan cheese

Instructions

Step 1: Preheat the oven to 375°F (190°C) and butter a baking dish.
Step 2: In a skillet, heat olive oil and 1 tablespoon of butter over medium heat. Add the sliced onions and cook, stirring often, until caramelized, about 25–30 minutes. Stir in the minced garlic and thyme, cooking for another minute.
Step 3: Add the remaining butter to the skillet. Stir in the flour to form a roux, cooking for 1–2 minutes without browning.
Step 4: Gradually whisk in the vegetable broth, then add milk and heavy cream, stirring continuously until smooth and thickened.
Step 5: Remove from heat and stir in the Gruyère, cheddar, and mozzarella cheeses until melted. Season the sauce with salt and black pepper.
Step 6: Toss the cooked elbow macaroni (cooked al dente) with the cheese sauce and caramelized onions.
Step 7: Transfer the mixture into the prepared baking dish. Combine breadcrumbs with grated Parmesan and sprinkle evenly over the top.
Step 8: Bake for 20–25 minutes until the casserole is bubbly and the topping is golden brown.
Step 9: Remove from oven and let cool slightly before serving. Enjoy your comforting French Onion Soup Mac & Cheese!

Tips & Variations

For deeper onion flavor, cook the onions slowly over low heat to avoid burning and maximize caramelization.
Swap vegetable broth with beef broth for a richer, meatier taste that mirrors classic French onion soup.
Sprinkle fresh chopped parsley or chives on top before serving for a fresh herbal note.
Use a mix of breadcrumbs and crushed toasted nuts for added texture in the topping.

Storage

Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven at 350°F (175°C) until warmed through to maintain the crispy topping. Alternatively, microwave individual portions, but the breadcrumb topping may lose crispness.

How to Serve

A close-up of macaroni and cheese with three layers visible: the top layer is golden brown with crispy, slightly burnt spots and scattered green herbs; beneath that is a thick layer of melted, gooey cheese stretching as a spoon lifts a portion, clinging to the curved pasta pieces; the bottom layer shows creamy cheese sauce coating the pale, soft elbow macaroni. The dish is served in a white bowl on a white marbled surface. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I make this recipe ahead of time?

Yes, you can assemble the mac and cheese up to the baking step, cover it, and refrigerate for up to 24 hours. Bake when ready and add a few extra minutes to the baking time if chilled.

What can I use if I don’t have Gruyère cheese?

Swiss cheese or Emmental make good substitutes for Gruyère, offering a similar melt and flavor. You can also increase the sharp cheddar slightly as a simpler option.