½ cup (8 tbsp / 1 stick / 125 g / 4.4 oz) butter
½ cup (70 g / 2.5 oz) flour
4 cups (1 L / 1.1 quart) milk, heated
1 cup (125 g / 4.4 oz) cheddar cheese
1 cup (125 g / 4.4 oz) Parmesan or Monterey Jack cheese
½ tsp cayenne pepper, or to taste
1 pound (450 g) macaroni noodles, boiled and drained
Make a roux using the butter and flour.
Add the heated milk, and whisk until smooth to complete the white sauce.
Mix in the cheese and cayenne pepper.
Mix the cheese sauce into the cooked macaroni noodles until well-coated.