Melt 2 tablespoons butter in a saucepan over medium heat
Whisk in 2 tablespoons all-purpose flour
Cook for 1 minute, stirring constantly
Slowly whisk in 1 cup 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 is fully melted and smooth
Add salt to taste
Add black pepper to taste
Add a pinch of garlic powder if desired
Pour over cooked macaroni and stir to combine