Step 1

Preheat the oven to 375°F and set an oven rack in the middle position. Grease a 2-qt baking dish with butter.

Step 2

Bring a large pot of salted water to a boil. Add the pasta and cook until al dente, or just slightly underdone. (It will continue to cook in the oven so you don't want it fully cooked.) Drain the pasta and rinse it with cold water.

Step 3

Meanwhile, melt 3 tablespoons of the butter in a medium (2-quart) pot over low heat. Add the flour and cook for 2 minutes, stirring with a whisk. While whisking, gradually add the milk. Bring to a boil, then reduce the heat to low and cook, uncovered, for a few minutes more, until thickened and smooth. Off the heat, whisk in the Gruyere, Cheddar, 1/4 cup Parmigiano-Reggiano, salt, pepper, and nutmeg. Add the cooked pasta and stir well. Pour into the prepared baking dish and set aside.

Step 4

In a small sauté pan over medium heat, melt the remaining tablespoon of butter. Add the panko and cook, stirring often, until golden brown. Stir in the herbes de Provence or thyme. Sprinkle the toasted panko mixture over the pasta and cheese sauce, followed by the remaining 2 tablespoons Parmigiano-Reggiano. Bake for 25 to 30 minutes, or until bubbly and golden brown.

Step 5

Note: To reheat leftovers, cover with aluminum foil and warm in a 300°F oven. Do not microwave.

Step 6

Freezer-Friendly Instructions: This can be frozen unbaked for up to 3 months. When you’re ready to cook it, defrost in the refrigerator for 24 hours, then proceed with the baking instructions in the recipe.