Cook macaroni in a large stock pot according to package directions; drain and return to pot.

Meanwhile, melt butter in a large saucepan over medium heat. When butter is bubbly, whisk in flour to form a paste. Cook, stirring constantly, for one minute. Slowly stir in milk and garlic. Cook, stirring, until mixture boils and thickens to desired consistency.

Add cheese, salt, and pepper to milk mixture. Stir until cheese is melted.

Pour cheese sauce over cooked macaroni and mix well to coat.