Cook the macaroni according to package instructions until al dente, then drain.
In a large saucepan, melt the butter over medium heat and stir in flour to create a roux.
Slowly whisk in the milk, ensuring no lumps remain, and bring to a gentle simmer.
Add the garlic powder, mustard powder, salt, and pepper to the mixture for flavor.
Remove the pan from heat and stir in the shredded cheddar and mozzarella until melted.
Incorporate the drained macaroni into the cheese sauce, mixing thoroughly.
Transfer the mac and cheese into a greased baking dish and spread evenly.
Optionally, sprinkle extra cheese on top and bake at 350°F (175°C) for 20-25 minutes until golden and bubbly.