Mac and Cheese

Preheat the oven to 375°F and set an oven rack in the middle position. Grease a 9x13-inch baking dish with butter.

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.

Meanwhile, melt 6 tablespoons of the butter in a medium 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, ½ cup Parmigiano-Reggiano, salt, pepper, and nutmeg. (If the cheese doesn't fully melt off the heat, it's okay to place the pan back over low heat, but do not let the sauce boil.) Add the cooked pasta and stir well. It will be very soupy; that's good. Pour into the prepared baking dish and set aside.

In a small skillet over medium heat, melt the remaining 2 tablespoons 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 tablespoon Parmigiano-Reggiano. Bake for 30 to 35 minutes, or until bubbly and golden brown.