Cook the macaroni for 4 minutes and spread them on a parchment paper-lined baking sheet to cool.
Return the macaroni to the pot and stir in cream, nutmeg, part of the cheeses, salt, and pepper.
Add the mixture to a greased baking dish and top with the remaining cheese, cover, and refrigerate for 12 to 24 hours.
Prepare the breadcrumbs by adding white bread to a food processor and mixing with melted butter.
Lay out the bread slices on a wire cooling rack the night before to let it get nice and stale.
Add the breadcrumb topping and bake.
