I love this recipe because it’s indulgent yet surprisingly simple to make. The slow-cooked onions bring out a natural sweetness that balances the salty, nutty flavors of the cheese. The broth-infused sauce adds incredible depth, while the crisp, golden topping gives it that perfect finishing touch. Whether I’m making it for a dinner party, a family meal, or just because I’m craving something comforting, this dish always impresses.
Ingredients
(Note: All ingredient amounts are listed in the recipe card below.)
Onion Base
▢ 3 large yellow onions, thinly sliced ▢ 3 tbsp butter ▢ 2 cloves garlic, minced ▢ 1 tsp dried thyme ▢ salt and freshly ground black pepper, to taste
Cheese Sauce
▢ 3 tbsp all-purpose flour ▢ 4 cups beef broth (or vegetable broth for vegetarian option) ▢ 1 cup half-and-half or heavy cream ▢ 1 ½ cups grated Gruyère cheese ▢ 1 cup sharp white cheddar cheese, grated
Pasta & Topping
▢ 12 oz elbow macaroni ▢ optional: French bread or baguette slices for toasting ▢ extra grated cheese for topping (about ½ cup)
Directions
Caramelize the onions
I start by heating butter in a large skillet over low heat. Then I add the sliced onions and cook them slowly for 30–40 minutes, stirring occasionally. I keep the heat low so the onions turn deeply golden and sweet without burning. Toward the end, I add the garlic and thyme, seasoning with salt and pepper to enhance the flavor.
Make the cheese sauce
Once the onions are caramelized, I sprinkle the flour over them and stir well to coat—it helps the sauce thicken later. Gradually, I whisk in the beef or vegetable broth, followed by the half-and-half or cream. I stir constantly until the mixture becomes smooth and slightly thickened. Then I add the Gruyère and sharp white cheddar, stirring until everything melts into a silky, creamy sauce.
Cook the macaroni
While the sauce simmers, I cook the elbow macaroni according to the package instructions until al dente. I drain the pasta, keeping a small cup of the pasta water aside in case I need to adjust the sauce’s consistency later.
Combine pasta and sauce
Next, I fold the cooked macaroni into the cheese sauce, making sure every piece of pasta is coated in that luscious, onion-filled sauce. If it feels too thick, I add a splash of the reserved pasta water to loosen it just slightly.
Bake or broil the topping
For an authentic French onion soup finish, I transfer the mac and cheese into an oven-safe dish, sprinkle it with extra cheese, and add a few toasted baguette slices on top. I broil it for a few minutes until the cheese bubbles and turns golden brown. I always keep an eye on it—broilers can brown quickly!
Servings and Timing
This recipe makes about 6 servings. Prep time: 15 minutes Cook time: 40 minutes Total time: 55 minutes
Variations
If I want a more robust flavor, I use a mix of Gruyère and fontina cheeses. For a lighter option, I substitute the half-and-half with whole milk. When I’m cooking for a crowd, I double the recipe and bake it in a large casserole dish topped with crushed garlic croutons instead of baguette slices—it’s always a hit.
Storage/Reheating
I store leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, I bake the mac and cheese at 350°F until warmed through, adding a splash of broth or cream to keep it creamy. I avoid microwaving because it can dry out the sauce and make the pasta rubbery.
FAQs
Can I make this ahead of time?
Yes! I prepare the dish up to the baking step, cover it tightly, and refrigerate. When I’m ready to serve, I bake until hot and bubbly.
Can I use different cheese?
Definitely. Swiss, fontina, or even mozzarella can replace Gruyère for a slightly different flavor.
How do I caramelize onions without burning them?
I keep the heat low, stir often, and let them cook slowly—it usually takes at least 30 minutes. Patience gives the best flavor.
Can I make it vegetarian?
Yes, I simply use vegetable broth instead of beef broth.
Can I add protein?
Sure. Shredded rotisserie chicken, or sautéed mushrooms work beautifully here.
Can I use pre-shredded cheese?
I prefer grating cheese myself because pre-shredded varieties often have anti-caking agents that prevent smooth melting.
What type of pasta works best?
Elbow macaroni is classic, but shells or cavatappi also hold the sauce nicely.
Why does my sauce get grainy?
It usually happens if the cheese is added when the sauce is too hot. I remove the pan from heat before stirring in the cheese.
Can I freeze it?
I don’t recommend freezing because cream-based sauces can separate when reheated.
What can I serve with it?
A simple green salad or roasted vegetables balances the richness perfectly.
Conclusion
I love how this French Onion Soup Mac & Cheese transforms familiar flavors into something truly special. The caramelized onions, rich broth, and creamy cheese sauce come together for a comforting dish that’s both elegant and cozy. Whether I serve it as a main course or a luxurious side, it’s always a showstopper—and a reminder that comfort food can be downright sophisticated.
A luxurious fusion of French onion soup and mac & cheese featuring deeply caramelized onions, Gruyère, and sharp white cheddar in a creamy broth-infused sauce, topped with golden cheese and toasted baguette slices.
Total Time:55 minutes
Yield:6 servings
Ingredients
Onion Base:
3 large yellow onions, thinly sliced
3 tbsp butter
2 cloves garlic, minced
1 tsp dried thyme
Salt and freshly ground black pepper, to taste
Cheese Sauce:
3 tbsp all-purpose flour
4 cups beef broth (or vegetable broth for vegetarian)
1 cup half-and-half or heavy cream
1 ½ cups grated Gruyère cheese
1 cup sharp white cheddar cheese, grated
Pasta & Topping:
12 oz elbow macaroni
½ cup extra grated cheese for topping
French bread or baguette slices, toasted (optional)
Instructions
In a large skillet over low heat, melt butter and add sliced onions. Cook slowly for 30–40 minutes, stirring occasionally until onions are deeply caramelized and golden brown.
Add garlic and thyme, then season with salt and pepper. Stir and cook 2 more minutes.
Sprinkle flour over the onions and stir to coat evenly. Gradually whisk in broth, then add half-and-half or cream. Stir constantly until the sauce thickens slightly.
Remove from heat and stir in Gruyère and sharp white cheddar until smooth and melted.
Meanwhile, cook macaroni according to package directions until al dente. Drain, reserving ½ cup of pasta water.
Fold the cooked pasta into the cheese-onion sauce until evenly coated. Add a splash of reserved pasta water if needed to loosen the sauce.
Transfer to an oven-safe dish, top with extra cheese, and arrange toasted baguette slices on top if using.
Broil for 2–4 minutes until the cheese bubbles and turns golden brown. Serve hot.
Notes
Use vegetable broth for a vegetarian version.
Grate cheese fresh for the smoothest sauce texture.
Cook onions low and slow for the best caramelization.
Add a touch of sherry or white wine to the onions for extra depth.
Top with garlic croutons instead of baguette slices for crunch.
