Recipe courtesy of Williams-Sonoma Kitchen.
Freshly made bread crumbs are the key to achieving a crisp, golden crust, the hallmark of perfect macaroni and cheese. You can make bread crumbs from slices of stale or fresh bread. Arrange the slices in a single layer on a baking sheet, place in a 300°F oven, and bake until they are completely dried and lightly toasted, 20 to 35 minutes. In a food processor, pulse the bread until the crumbs reach the desired consistency, then season with salt and pepper. You can also flavor them with butter or extra-virgin olive oil and fresh herbs or minced garlic.
Feel free to substitute another cheese for the Cheddar. Gruyere, fontina and Emmentaler are good choices.