Melt Butter: Over medium heat, in a large pan, melt the butter.
1 stick (1/2 cup) unsalted butter
Add Flour: Whisk in the flour and cook for 1-2 minutes.
1/2 cup + 1 Tablespoon all purpose flour
Add Dairy: Add in evaporated milk and regular milk.
12 ounces (1 1/2 cups) evaporated milk*, 3 1/2 cups milk*
Dissolve Flour: Whisk until the flour dissolves.
Add Spices & Hot Sauce: Add hot sauce, garlic, onion, mustard powder, salt, and pepper.
1 Tablespoon hot pepper sauce*, 2 teaspoons granulated garlic, 1 teaspoon onion powder, 1 teaspoon ground mustard, 1 teaspoon salt,, fresh cracked black pepper
Combine Spices: Whisk until spices are combined.
Simmer Sauce: Continue stirring and simmering the sauce (not boiling) until it thickens enough to coat the back of a spoon (about 4 minutes). It will continue to thicken when you add the cheese.
8 ounces swiss cheese*, 8 ounces mild or sharp cheddar cheese,, 4 ounces gruyere,, 16 - 20 ounces pasta