Preheat the oven to 350 degrees F.
Cook the macaroni to al dente in a large pot of boiling water. Drain, rinse with cold water and set aside.
In a separate pot, warm the milk over medium heat; be careful not to let it boil.
Melt the butter in a large saucepan over medium heat. Add the flour and cook for 5 minutes, whisking constantly. Add the warmed milk and cook, stirring, until the sauce coats a spoon.
Add the cheddar, Gruyere, salt, nutmeg, black pepper and cayenne and mix well. Add the macaroni and stir to coat with sauce.
Pour the mixture into a buttered 9-inch baking dish and bake for 45 minutes. Set aside to cool, then refrigerate overnight.
When ready to serve, unmold the mac 'n' cheese from the baking dish and cut it into twelve equal cubes. Roll the cubes in the breadcrumbs and fry them in the clarified butter in a large skillet until brown and crispy on all sides and melted on the inside. Enjoy!
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.