Simmer macaroni in milk: Warm milk in a saucepan until steamy. Add dry macaroni, bring to a boil, then reduce to a simmer. Cook for 15 minutes, stirring occasionally, until macaroni is tender and has soaked up almost all the milk, being mindful of potential foaming.
Preheat the oven to 400°F. In a saucepan, melt butter and mix in grated cheese, black pepper to taste, and a pinch of freshly grated nutmeg when the macaroni is almost ready.
Combine the melted cheese sauce with the cooked macaroni and milk, stirring until well mixed. Taste and season with salt as desired.
Sprinkle breadcrumbs over the mac and cheese mixture and bake at 400°F for 20 minutes until golden brown. Add cayenne for extra flavor.