The rich, delicious flavors of a classic French onion soup infuse this sharp and creamy mac and cheese to create a truly extraordinary dish.
Bonjour! Do you love classic French food? Or are you more partial to good old American comfort casseroles? What do you think would happen if there was a mashup between the two? You might just get French onion mac and cheese, a mouthwatering dish that will make you exclaim ooh la la! The best parts of French onion soup—caramelized onions, Gruyère, and bread (crumbs, in our case here)—combine with everything we love in a baked mac and cheese to produce a foodie phenomenon that is at once familiar and yet something entirely new.
French onion mac and cheese is, in a word, luxurious. The beautifully caramelized onions bring a rich complexity to the sauce, made with two kinds of cheeses, and the mix of textures—soft yet substantial, velvety and creamy—is divine. This mashup turns two iconic comfort foods into something elegant and sumptuous, but that doesn’t mean it isn’t a great choice for a casual weeknight meal.
Though it does take some time, I’m not going to lie. That said, it’s time very well spent. Onions are naturally sweet, and caramelizing them, which will take 40 minutes or so, yields the most wonderful, deep flavor. And speaking of flavor, the delectable sauce is made from both sharp cheddar and nutty Gruyère and enhanced by mustard powder and umami-forward Worcestershire sauce, but it takes some loving care. You’ll have to make a roux first, then slowly whisk in the milk and cook until it is thickened. Then, you’ll stir in the cheeses until they melt into the sauce. When everything is mixed with the al dente pasta, you’ll top the whole thing with crunchy panko breadcrumbs and more shredded cheese. But all of this effort is an investment in your culinary happiness. One bite, and you’ll see why it was worth every minute.
Caramelizing Onions
The caramelization process results in onions that are sweet and savory, jammy, and meltingly soft, with a beautiful dark color. The cook is low and slow, which is one reason why we use a combination of butter and olive oil: we want the flavor from butter, but it has a tendency to burn. Olive oil has a higher smoke point, so using these two fats together to cook our onions will give them plenty of time to develop their delicious flavor.
Beyond butter, olive oil, and onions, the only other thing you will need is patience. It will take at least 40 minutes for the onions to achieve that perfect tenderness and golden brown caramelization. Stir them periodically, but gently, as they cook. It’s well worth the wait.
How Do I Store Leftovers?
Cooled to room temperature, French onion mac and cheese can be stored in an airtight container in the refrigerator for up to 4 days or in the freezer for up to 3 months. Thaw overnight in the fridge before reheating.
Can I Prep This Ahead?
The cooled caramelized onions can be stored in an airtight container in the refrigerator for up to a week and in the freezer for up to 3 months. You can also prepare French onion mac and cheese through step 17, cover it tightly with aluminum foil, and keep it in the fridge for up to 2 days before baking. You can freeze the covered, unbaked French onion mac and cheese for up to 3 months, but it will be susceptible to freezer burn, and the texture might be altered. Thaw overnight in the fridge before baking.
Serving Suggestions
You know how I love a themed meal, so let’s keep things French! Although it might seem like onion overload, I love a casual meal made up of French Onion Soup, a Green Salad dressed with French Dressing (which isn’t really French, but the sweet and tart flavor works really well with this meal), French onion mac and cheese, and slices of crusty Boule spread with creamy Homemade Boursin.
But an upscale, more elaborate meal is also a perfect occasion for French onion mac and cheese. Serve it with either Beef Bourguignon or Coq Au Vin, and some Ratatouille, this delicious rosemary Fougasse, with Homemade Butter, and a Chocolate Mousse Cake for dessert. Bon appétit!
French Onion Mac And Cheese
Ingredients
- 4 tablespoons unsalted butter divided
- 2 tablespoons olive oil
- 3 large yellow onions thinly sliced
- 1 teaspoon salt divided
- 1/2 teaspoon black pepper divided
- 1 teaspoon fresh thyme leaves
- 1 pound rigatoni or cavatappi
- 3 1/2 tablespoons all-purpose flour
- 4 cups whole milk
- 1 teaspoon dry mustard powder
- 1 1/2 tablespoons Worcestershire sauce
- 12 ounces shredded Gruyère cheese
- 12 ounces shredded sharp cheddar cheese
- 1 cup panko breadcrumbs
- Fresh parsley chopped (for garnish)
Instructions
- In a large skillet over medium heat, melt 2 tablespoons of butter with the olive oil.
- Add the sliced onions to the skillet.
- Sprinkle with 1/2 teaspoon of salt and 1/4 teaspoon of black pepper.
- Cook the onions over medium-low heat, stirring often, until they are golden brown and caramelized, about 40 minutes.
- Stir in the fresh thyme leaves during the last few minutes of cooking. Set aside.
- While the onions are cooking, bring a large pot of salted water to a boil. Cook the pasta according to the package instructions until al dente.
- Drain the pasta and set it aside.
- Preheat your oven to 425°F.
- In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter.
- Add the flour and whisk constantly for 2 minutes to make a roux.
- Slowly whisk in the whole milk until the mixture is smooth.
- Stir in the dry mustard powder, Worcestershire sauce, remaining 1/2 teaspoon of salt, and remaining 1/4 teaspoon of black pepper.
- Keep cooking the sauce, stirring frequently, until it thickens and coats the back of a spoon, around 5 minutes.
- Take the sauce off the heat. Set aside 1/4 cup of grated cheddar cheese for topping. Then, stir in the rest of the shredded Gruyère and cheddar cheeses until fully melted and smooth. Adjust salt and pepper as needed.
- Combine cooked pasta, caramelized onions, and cheese sauce in a large bowl. Mix well to coat evenly.
- Grease a 9×13-inch baking dish. Pour the mixture into the dish and spread it evenly.
- Sprinkle the panko breadcrumbs evenly over the top of the pasta, followed by the remaining cheese.
- Cover with foil and bake in the preheated oven for 20-25 minutes, or until the sauce is bubbly. Remove foil during the last 5 minutes of baking to help brown the top.
- Let the mac and cheese cool for a few minutes before serving. Garnish with fresh parsley.
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