Preheat oven to 350°F and butter a 9×13-inch baking dish.
Boil macaroni for 2 minutes less than al dente. Drain.
Melt butter, stir in flour, and cook until golden, about 1.5 minutes.
Gradually add milk, whisking to prevent lumps, then simmer until thickened.
Remove from heat and stir in cheese, salt, and pepper until smooth.
Mix in pasta to fully coat with sauce.
Transfer half to baking dish, top with half reserved cheese. Repeat.
Bake 10–15 minutes until bubbly and golden. Sprinkle paprika if desired.
