Macaroni and Cheese Gratin Recipe

Once the water is boiling, add 1/2 teaspoon salt and the 1 pound elbow macaroni. Cook it until it's not quite al dente; the macaroni will continue to cook in the oven, so you want it slightly firm.

Meanwhile, in a separate pot, melt the 1 tablespoon butter. Add the 1 tablespoon flour and stir with a whisk or wooden spoon for a couple of minutes, cooking out the raw flour taste to form a roux.

Gradually whisk in the 4 cups milk, about 1/2 cup at a time, making sure each addition is incorporated and the mixture thickens before adding more. Continue cooking over low heat, stirring constantly and scraping the bottom of the pan to prevent scorching, until the sauce is thick enough to coat a spoon.

Once the sauce has thickened, stir in the 2 cups grated cheddar and 2 cups grated Gruyère until they've completely melted into the sauce. Season with 1/4 teaspoon nutmeg, 3 drops pepper sauce, and the remaining 1/2 teaspoon salt. Remove the sauce from the heat and set it aside.

When the macaroni is cooked to your desired firmness, drain it thoroughly in a colander and return it to its pot.

Transfer the macaroni and cheese mixture into individual gratin dishes or a large buttered baking dish. If you're adding tomato slices, tuck a few in with a knife either halfway through filling the dish or at the very end. Don't smooth out the top; let a few peaks remain, as these will crisp up nicely as it bakes.

For the topping, melt the 1 tablespoon butter. Pour it over the 1 1/2 cups herbed bread crumbs in a bowl and mix well to combine. Sprinkle this mixture evenly over the macaroni and cheese.