Melt 2 tablespoons butter in a saucepan over medium heat
Whisk in 2 tablespoons all-purpose flour
Cook for 1 minute, whisking constantly
Slowly pour in 1 1/2 cups milk while whisking
Cook until the mixture thickens, about 3 to 5 minutes
Reduce heat to low
Stir in 2 cups shredded cheese
Add salt to taste
Add black pepper to taste
Stir until the sauce is smooth
Use immediately with cooked macaroni