Bring a large pot of salted water to boil and cook the elbow macaroni according to package instructions until al dente. Drain the pasta and set aside.

In a medium saucepan, melt 4 tablespoons of unsalted butter over medium heat.

Add 1/4 cup of all-purpose flour to the melted butter, whisking continuously for about 1 minute until smooth.

Gradually pour in 2 cups of milk while whisking vigorously until the mixture thickens and becomes creamy.

Stir in 2 cups of shredded sharp cheddar cheese and 1 cup of shredded mozzarella cheese until completely melted.

Sprinkle in 1/2 teaspoon of garlic powder, 1/2 teaspoon of onion powder, and salt and pepper to taste. Stir well.

Gently fold the creamy cheese sauce into the cooked elbow macaroni until well-coated.

Transfer the mixture to a greased baking dish and bake at 350°F (175°C) for about 20 minutes.