Introduction

This French Onion Soup Mac & Cheese is a comforting twist on two classic favorites. Rich caramelized onions, a blend of melted cheeses, and a crispy breadcrumb topping make this dish irresistibly flavorful and cozy.

A close-up of a cast iron pan filled with golden macaroni and cheese. The dish has several layers of creamy melted cheese that is stringy and stretchy, covering the soft pasta beneath. There are small bits of toasted breadcrumbs on top, adding a crunchy texture with some fresh green herbs lightly sprinkled for color contrast. The warm, rich cheese is slightly browned in spots, showing the perfect baked finish. The background is a 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 your oven to 375°F (190°C) and butter a baking dish to prevent sticking.
Step 2: In a skillet, heat the olive oil and 1 tablespoon of butter over medium heat. Add the sliced onions and cook, stirring often, until caramelized and deep golden brown, about 25–30 minutes. Stir in the minced garlic and thyme and cook for another minute.
Step 3: Add the remaining 2 tablespoons of butter to the skillet with the onions. Sprinkle flour over the mixture and stir constantly to form a roux. Slowly whisk in the vegetable broth, then the milk and heavy cream until the sauce is smooth and thickened.
Step 4: Stir in the Gruyère, sharp cheddar, and mozzarella cheeses until melted. Season the cheese sauce with salt and black pepper to taste.
Step 5: Cook the elbow macaroni in salted boiling water until just al dente, then drain and toss it into the cheese sauce along with the caramelized onions.
Step 6: Transfer the cheesy pasta mixture into the prepared baking dish. In a small bowl, mix together the breadcrumbs and grated Parmesan cheese, then sprinkle evenly over the top.
Step 7: Bake in the preheated oven for 20–25 minutes, or until the top is bubbly and golden brown.
Step 8: Let the dish rest for 5 minutes before serving. Garnish with fresh thyme if desired, and serve hot for a comforting meal.

Tips & Variations

For added depth, use beef broth instead of vegetable broth to echo traditional French onion soup flavors.
Try adding a splash of white wine while caramelizing onions for extra richness.
Use panko breadcrumbs for an even crispier topping.
Substitute thyme with rosemary or sage for a different herbal note.

Storage

Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven or microwave until warmed through, adding a splash of milk to loosen the sauce if needed.

How to Serve

A close-up of a skillet filled with creamy macaroni and cheese, showing three visible layers. The bottom layer has golden browned macaroni pasta with a slightly crispy texture. The middle layer is thick, melted cheese that stretches in long strings as a woman's hand lifts a portion. The top layer has a bubbly, browned cheese crust sprinkled with small bits of herbs. The skillet is placed 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 dish ahead of time?

Yes, you can prepare the macaroni and cheese mixture and bake it just before serving. Alternatively, assemble it fully and refrigerate; bake directly from the fridge, adding a few extra minutes to the baking time.

What can I use instead of Gruyère cheese?

If Gruyère is unavailable, Swiss cheese or Emmental make great substitutes, offering a similar nutty and creamy flavor.