Bring a large pot of salted water to a boil, then cook the elbow macaroni according to package instructions. Once al dente, drain and set aside.

In a medium saucepan over medium heat, melt the butter until fully liquid.

Stir in the all-purpose flour and cook for 1-2 minutes until light golden brown to form a roux.

Gradually pour in the milk while whisking continuously to prevent lumps, cooking until thickened, about 5-7 minutes.

Remove from heat and stir in the shredded cheddar and grated Parmesan until fully melted.

Add salt, black pepper, and garlic powder to the cheese mixture and mix well.

Gently fold the cooked macaroni into the creamy cheese sauce.

Transfer to a serving dish and enjoy immediately.