Cook pasta: Bring a large pot of water to a boil. Add salt and macaroni. Cook them according to the package instructions.
While the pasta cooks, make the white cheddar sauce.
Grate the cheese on a box grater and set it aside.
Roux: Melt the butter in the saucepan or Dutch oven. Add the flour and stir it into the butter for about 2 minutes; it should get golden but not brown.
Gradually add the milk and heavy cream while whisking continuously to avoid clumps. Keep whisking on medium heat until the sauce thickens and coats the back of a spoon; it will take 3 to 5 minutes.
Season with garlic powder, salt, and pepper.
Add cheese: Turn the heat to low. Add the cheese and stir until melted. Turn off the heat.
Reserve about ½ cup of the pasta water and drain the rest.
Combine macaroni with the sauce. If the sauce is too thick, add a little of the reserved pasta water and stir again. Add just as much water as needed; you don’t have to add it all.
Adjust the taste with salt and pepper and serve immediately.
Notes
The recipe can be easily doubled.
Use any other short pasta, for instance, farfalle, fusilli, cavatappi, or penne.
Salted or unsalted and use salt accordingly.
You can replace it with crème Fraiche or cream cheese.