Description
A rich and comforting French Onion Mac and Cheese combining deeply caramelized onions with creamy Gruyere cheese sauce and baked to perfection with a crunchy panko topping. This casserole offers classic French onion flavors in a cheesy pasta dish that's perfect for a cozy gathering or special occasion.
Ingredients
Scale
Caramelized Onions
- 4 tablespoons unsalted butter - divided
- 4 large yellow onions - peeled and sliced
- 2 tablespoons balsamic vinegar
- 2 teaspoons fresh thyme leaves
- A splash of beef broth or water - only if needed
Mac and Cheese
- 1 pound cavatappi pasta
- ½ cup unsalted butter
- ⅓ cup all-purpose flour
- 4 cups whole milk - plus more as needed
- 16 ounces freshly shredded Gruyere cheese - divided (about 4 cups)
- 1 teaspoon dijon mustard
- 1 teaspoon garlic powder - or to taste
- Salt and pepper - to taste
Panko Breadcrumb Topping
- ⅓ cup panko breadcrumbs
- 3 tablespoons olive oil
Instructions
- Caramelize the Onions: In a large deep pan, melt 2 tablespoons of butter over medium heat. Add the sliced onions with a pinch of salt and cook for 15 minutes to start softening. Lower heat to medium-low and cook, stirring occasionally, until the onions are deeply caramelized and golden brown, about 30 more minutes. If needed, add a splash of broth or water to deglaze the pan. In the last 5 minutes, add the remaining 2 tablespoons butter, balsamic vinegar, and thyme, stirring until onions are golden and flavorful. Set aside.
- Cook Pasta: Preheat oven to 375 degrees F. Cook the pasta according to package instructions until just al dente, then drain and rinse with cold water to stop cooking. Set aside.
- Make Cheese Sauce: In a large pot, melt ½ cup of butter over medium heat. Whisk in the flour and cook for 2-3 minutes to form a roux with a nutty aroma. Gradually add milk while whisking to prevent lumps. Cook until thickened over medium-low heat. Season with dijon mustard, garlic powder, salt, and pepper. Stir in 3 cups of Gruyere cheese until melted and smooth.
- Combine Pasta and Sauce: Add the cooked pasta to the cheese sauce, stirring to coat evenly.
- Prepare Breadcrumb Topping: In a small bowl, mix panko breadcrumbs with olive oil. Set aside.
- Assemble the Dish: Transfer half of the mac and cheese to a 9x13 baking dish. Gently fold in most of the caramelized onions and 1 cup of the remaining shredded Gruyere. Layer the rest of the mac and cheese on top, then sprinkle the reserved onions, cheese, and panko breadcrumb mixture evenly over the surface.
- Bake: Place the baking dish on a large sheet pan to catch any drips and bake uncovered at 375 degrees F for 25 minutes or until bubbly and golden on top. Let cool slightly before serving.
Notes
- Cook pasta until just al dente since it continues cooking in the oven.
- Use yellow onions for their mild, sweet flavor; avoid red onions for caramelizing.
- Use a large deep pan for caramelizing onions to prevent overcrowding and steaming.
- Patience is key—allow onions 40-45 minutes to properly caramelize for best flavor.
- Grate your own Gruyere cheese to avoid starch additives found in pre-shredded varieties.
- Caramelized onions can be made 2 days ahead and refrigerated.
- The casserole can be assembled a day ahead without the breadcrumb topping, then topped and baked before serving.
- Freeze the assembled dish for up to 2 months; thaw overnight in fridge and reheat with a splash of milk for creaminess.
- Substitute Gruyere with Swiss, gouda, or white cheddar if preferred.
- Other pasta shapes like shells, fusilli, or rigatoni work well too.
Nutrition
- Serving Size: 1 serving
- Calories: 480 kcal
- Sugar: 6 g
- Sodium: 320 mg
- Fat: 24 g
- Saturated Fat: 14 g
- Unsaturated Fat: 8 g
- Trans Fat: 0.5 g
- Carbohydrates: 50 g
- Fiber: 3 g
- Protein: 18 g
- Cholesterol: 70 mg
