Ingredients
Scale
- 2 tablespoons olive oil
- 4 large yellow onions, thinly sliced
- 1 teaspoon granulated sugar
- 1/2 teaspoon salt, plus more to taste
- 1/4 teaspoon black pepper, plus more to taste
- 4 tablespoons unsalted butter
- 4 tablespoons all-purpose flour
- 3 cups whole milk, warmed
- 1 teaspoon Dijon mustard
- 1/4 teaspoon freshly grated nutmeg
- 2 cups high-quality beef broth (or vegetable broth for vegetarian option)
- 1 pound elbow macaroni or cavatappi pasta
- 8 ounces Gruyère cheese, shredded (about 2 cups), divided
- 6 ounces sharp cheddar cheese, shredded (about 1 1/2 cups)
- 1/2 cup grated Parmesan cheese
- Crusty bread or croutons, for serving (optional)
Instructions
- Begin by caramelizing the onions: Heat olive oil in a large, heavy-bottomed pot or Dutch oven over medium-low heat. Add the thinly sliced onions, sugar, salt, and pepper. Cook, stirring occasionally, for 35-45 minutes, or until the onions are deeply golden brown, very soft, and sweet. If they start to stick, add a tablespoon or two of water to deglaze the pan. Set aside once caramelized.
- While onions cook, bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente. Drain well and set aside.
- Preheat your oven to 375°F (190°C). Grease a 9×13 inch baking dish or 6 individual oven-safe crocks.
- Prepare the béchamel base: In the same pot used for the onions (or a clean one), melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to create a roux. Gradually whisk in the warm milk, ensuring no lumps form. Continue whisking until the sauce thickens, about 5-7 minutes. Stir in the Dijon mustard and nutmeg.
- Build the cheese sauce: Slowly whisk in the beef broth. Reduce heat to low. Add 1 1/2 cups of the shredded Gruyère, all of the cheddar cheese, and the Parmesan cheese, stirring constantly until melted and smooth. Season with additional salt and pepper to taste.
- Combine and bake: Stir the cooked pasta and the caramelized onions into the cheese sauce until everything is evenly coated. Pour the mixture into the prepared baking dish or individual crocks. Sprinkle the remaining 1/2 cup of shredded Gruyère evenly over the top.
- Bake for 20-25 minutes, or until the mac & cheese is bubbly around the edges and the cheese topping is golden brown and melted. For an extra golden crust, you can briefly broil for 1-2 minutes, watching carefully to prevent burning. Let rest for 5-10 minutes before serving. Serve hot, optionally with crusty bread or croutons.
Notes
Leftovers can be stored in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven or microwave, adding a splash of milk if needed to restore creaminess. For a vegetarian version, simply substitute vegetable broth for beef broth. A pinch of fresh thyme added to the caramelized onions would also be a lovely aromatic addition.
- Prep Time: 20 minutes
- Cook Time: 50 minutes
- Category: Main Course
- Method: Baking
- Cuisine: French-American Fusion
Nutrition
- Serving Size: 1 serving
- Calories: 580
- Sugar: 8g
- Sodium: 750mg
- Fat: 35g
- Saturated Fat: 20g
- Unsaturated Fat: 10g
- Trans Fat: 0g
- Carbohydrates: 45g
- Fiber: 4g
- Protein: 28g
- Cholesterol: 105mg