Melt 2 tablespoons butter in a pan over medium heat
Add 2 tablespoons all-purpose flour
Whisk continuously for 1 to 2 minutes
Slowly pour in 2 cups milk while whisking
Cook and whisk until the sauce thickens
Add salt to taste
Add black pepper to taste
Add a pinch of nutmeg if desired
Stir in grated cheese if desired
Mix with cooked pasta immediately