Ingredients
- Elbow macaroni (1 pound)
- Yellow onions (3 large, thinly sliced)
- Gruyère cheese (2 cups, freshly shredded)
- Beef broth (4 cups, low sodium)
- Unsalted butter (6 tablespoons)
- All-purpose flour (1/4 cup)
- Whole milk (2 cups)
- Baguette slices (4 slices, lightly toasted)
Instructions
- Step 1: Caramelize the onions and cook the pasta. Melt 2 tablespoons of butter in a large pot over medium-low heat and add the sliced onions. Cook slowly, stirring occasionally, for 45–60 minutes until the onions are deeply caramelized and brown. While the onions cook, boil the macaroni according to package directions until very al dente (about 2 minutes less than instructed); drain and set aside.
- Step 2: Build the soup base. Once the onions are caramelized, pour in the 4 cups of beef broth and scrape up any brown bits from the bottom of the pan. Bring to a simmer for 5 minutes, allowing the liquid to reduce slightly, then remove the broth and onions from the heat and set aside.
- Step 3: Prepare the cheese sauce (Mornay). In a separate saucepan, melt the remaining 4 tablespoons of butter over medium heat. Whisk in the flour to create a roux and cook for 1 minute. Slowly whisk in the whole milk until smooth. Bring the sauce to a gentle simmer, stirring constantly until thickened, then remove from heat. Stir in 1.5 cups of the shredded Gruyère until fully melted and smooth, reserving the remaining cheese for the topping.
- Step 4: Combine and prepare for baking. Preheat your oven to 400°F (200°C). Pour the concentrated beef broth and caramelized onion mixture into the Mornay sauce, stirring well to combine the "soup" flavor into the cheese sauce. Add the al dente macaroni to the sauce, tossing gently until every noodle is coated, then transfer the mixture to a greased 9×13 inch baking dish.
- Step 5: Top and bake. Sprinkle the remaining 1/2 cup of Gruyère cheese over the mac and cheese. Place the toasted baguette slices on top of the cheese layer (mimicking the traditional soup crouton). Bake for 15–20 minutes, or until the sauce is bubbly and the top is golden brown. Let rest for 5 minutes before serving.
Notes
- If storing leftovers, tightly cover the dish and consider reserving a few spoonfuls of the concentrated beef broth mixture to stir in before reheating, which will help keep the sauce from drying out.
- For best results, reheat individual portions in the oven at 300°F (150°C) covered with foil until warmed through; microwaving tends to make the Gruyère rubbery.
- Serve this ultra-rich dish alongside a crisp, peppery green salad dressed simply with balsamic vinegar and olive oil to balance the savory flavor depth.
- Do not rush Step 1; the integrity of the "soup" flavor depends entirely on achieving a deep, mahogany brown caramelization of the onions, which requires the full 45–60 minute cook time.
- Prep Time: 15 minutes
- Cook Time: 20 minutes
- Method: Stovetop
- Cuisine: American