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

In a saucepan, melt the butter over medium heat. Stir in the flour and cook for 1-2 minutes until golden.

Gradually whisk in the milk, stirring constantly until the mixture thickens.

Remove from heat and stir in the cheddar and mozzarella cheeses until melted and smooth. Season with garlic powder, onion powder, salt, and pepper.

In a large bowl, combine the cooked pasta and cheese sauce, mixing well.

Transfer to a baking dish and top with additional cheese and desired toppings.

Bake in a preheated oven at 350°F (175°C) for 15-20 minutes until bubbly and golden.

Serve hot with a variety of toppings for guests to customize their mac and cheese.