Step 1

Heat a large pot to boiling and cook the macaroni for the time instructed on the packaging minus 1 minute (ie. if the instructions say cook for 9 minutes, cook for 8 minutes). Reserve 2 cups of pasta water and drain.

Step 2

To the now empty pot, heat the butter over medium heat until melted and foaming. Add the flour and whisk until no clumps remain. Whisk in the mustard powder until combined.

Step 3

Stir in the two milks until combined. Bring to a boil and reduce heat to low to simmer. Simmer until thickened.

Step 4

With the heat on low, add the American cheese, ½ cup at a time, and stir using an 8 figure motion until mostly melted before adding the next ½ cup. Repeat with the remaining cheeses.

Step 5

Pour the cooked macaroni into the cheese sauce and stir until fully coated. If the cheese sauce is too dry, add in the reserved pasta water ¼ cup at a time until the desired consistency is reached. Serve immediately.