Melt the butter in a large pot over medium heat. Add the flour, then whisk until combined, about 30 seconds.
Pour in the water and whisk until smooth and just thickened.
Add the milk and whisk until combined.
Stir in the macaroni, salt, garlic powder, onion powder, smoked paprika and pepper, then bring the mixture to a simmer.
Cook for 8-10 minutes, stirring occasionally, until pasta is done.
Turn the heat to low, then stir in the cheeses. Keep stirring until the sauce is smooth. Sprinkle with parsley and serve.
Video
Notes
Skip the bags of pre-shredded cheese and grate your own. The prepared shredded cheeses often contain preservatives and anti caking agents and do not melt smoothly.
This is a thick and cheesy mac! If you prefer a thinner sauce, add more milk, one tablespoon at a time until you've reached your desired consistency.