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: Heat olive oil and 1 tablespoon of butter in a skillet over medium heat. Add the sliced onions and cook, stirring often, until caramelized, about 25–30 minutes. Stir in the minced garlic and thyme.

Step 3: Add the remaining butter to the skillet. Stir in the flour to make a roux, cooking for about 1–2 minutes until lightly golden.

Step 4: Slowly whisk in the vegetable broth, then add the milk and heavy cream. Continue whisking until the sauce is smooth and begins to thicken.

Step 5: Stir in the Gruyère, cheddar, and mozzarella until the cheeses melt completely. Season the sauce with salt and black pepper.

Step 6: Cook the elbow macaroni according to package instructions until al dente. Drain and toss with the cheese sauce and caramelized onions.

Step 7: Transfer the macaroni mixture to the prepared baking dish. Combine the breadcrumbs with the grated Parmesan and sprinkle evenly over the top.

Step 8: Bake in the preheated oven for 20–25 minutes until the topping is golden and bubbly.

Step 9: Let the dish rest for 5 minutes. Garnish with fresh thyme and serve hot.

Tips & Variations

For deeper onion flavor, use a mix of yellow and sweet onions or add a splash of dry white wine during caramelizing.

If you prefer a crispier topping, broil the breadcrumbs and cheese for 1–2 minutes at the end of baking, watching carefully to avoid burning.

Substitute vegetable broth with beef broth for a richer taste closer to traditional French onion soup.

Use gluten-free pasta and flour if you need to make this dish gluten-free.

FAQs

Can I make this recipe ahead of time?

Yes, you can prepare the mac and cheese mixture and store it before baking. Just cover and refrigerate, then add the breadcrumb topping and bake when ready to serve.

What cheeses work best in this recipe?

Gruyère provides a nutty, meltable base, while sharp cheddar adds tangy flavor and mozzarella offers stretchiness. These three combined create a rich and balanced cheese sauce.