Melt 2 tablespoons butter in a saucepan over medium heat
Whisk in 2 tablespoons all-purpose flour
Cook for 1 minute, whisking constantly
Slowly whisk in 1 1/2 cups milk
Cook until the mixture thickens, stirring often
Reduce heat to low
Add 1 1/2 to 2 cups shredded cheese
Stir until the cheese melts and the sauce is smooth
Season with salt and black pepper
Mix with cooked macaroni immediately