Cook pasta in salted water until al dente. Get them out of the water. Preheat the oven to 360F. Melt the butter in a saucepan.
Add all-purpose flour, salt, pepper, and nutmeg. Mix thoroughly.
Pour in the milk and keep stirring. Make sure to stir constantly as you pour the milk. The result should be a homogeneous white sauce without lumps.
Add 1 cup of cheese and stir. Heat 3 more minutes until the cheese is completely melted.
Add pasta to the skillet and stir to coat completely. Transfer pasta with sauce to a baking dish and flatten.
Mix the remaining cheese with breadcrumbs and put on top of the pasta. Put the baking dish in the oven and cook for 25 minutes. Cut the finished macaroni and cheese into portions and serve.