Fill a large pot with water, add a pinch of salt, and bring to a rolling boil.

Add the dry elbow pasta and cook according to package instructions until al dente (about 7 to 9 minutes).

Drain the pasta using a colander and set it aside.

Heat a skillet or large saucepan over medium-low heat and add the butter.

Stir with a whisk until the butter has melted and is bubbling gently.

Add the all-purpose flour and whisk continuously until well-combined and slightly golden (about 1 minute).

Gradually incorporate milk, whisking to avoid lumps, and then reduce heat to low.

Allow the mixture to simmer gently, stirring occasionally until it thickens (a few minutes).

Whisk in salt, ground mustard, garlic powder, and cayenne pepper.

Remove from heat and stir in cheddar and American cheese until melted and smooth.

Carefully fold in the cooked pasta, ensuring all pieces are well-coated with the cheese sauce.

Taste and adjust seasoning with additional salt and pepper if needed.

Serve immediately in bowls, optionally garnished with herbs or additional cheese.