Introduction

French Onion Soup Mac & Cheese is a comforting twist on two classic favorites. This rich, cheesy casserole combines deeply caramelized onions with a creamy blend of Gruyère, cheddar, and mozzarella. It’s perfect for cozy evenings when you want something both familiar and full of flavor.

The image shows a close-up of macaroni and cheese in a white dish, with a woman's hand lifting a forkful of the dish. The mac and cheese has clearly two layers: a top layer that is golden brown and crispy with spots of darker browning, and underneath it, a creamy, rich sauce coating tender, slightly curved pasta. The cheese sauce looks smooth and stretchy, dripping slightly from the pasta on the fork. Scarce green herbs are sprinkled lightly on top, adding small flecks of color. The dish sits on a white marbled surface. 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, divided
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 to prepare for baking.
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, cooking for another minute until fragrant.
Step 3: Add the remaining butter to the skillet. Stir in the flour to make a roux, cooking for 1–2 minutes until lightly golden.
Step 4: Slowly whisk in the vegetable broth, then add the milk and heavy cream, stirring constantly until smooth and slightly thickened.
Step 5: Stir in the Gruyère, cheddar, and mozzarella cheeses until melted and fully combined. Season the sauce with salt and black pepper.
Step 6: Cook the elbow macaroni al dente according to package instructions, drain, and toss it with the cheese sauce and caramelized onions.
Step 7: Transfer the macaroni mixture to the prepared baking dish. In a small bowl, combine breadcrumbs with grated Parmesan and sprinkle evenly over the top.
Step 8: Bake for 20–25 minutes until the topping is golden and the dish is bubbly.
Step 9: Let the mac and cheese rest for 5 minutes before garnishing with fresh thyme and serving hot.

Tips & Variations

Use fresh thyme if possible for a brighter flavor; dried thyme works well in a pinch.
For extra depth, add a splash of dry white wine to the onions while caramelizing.
Try swapping the vegetable broth for beef broth for a more traditional French onion flavor.
Mix in cooked bacon or caramelized mushrooms for added texture and taste.

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 the crispy topping, or microwave in short intervals, stirring occasionally. This dish doesn’t freeze well due to the cream and cheese sauce.

How to Serve

A close-up view of creamy macaroni and cheese in a white dish, showing a top layer of golden brown melted cheese with small dark browned spots and green herb flecks. The dish is full of elbow-shaped pasta covered in thick, gooey, stretchy white cheese sauce that pulls away in strings as a spoon lifts a bite. The rich texture of the melted cheese contrasts with the smooth pasta beneath, all placed on a white marbled surface in soft light. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use other types of pasta?

Yes, while elbow macaroni is classic, other pasta shapes like shells or cavatappi work well since they hold the cheese sauce nicely.

How can I make this recipe vegetarian?

This recipe is already vegetarian as long as you use vegetable broth and ensure the cheese does not contain animal rennet.