3 creamy macaroni cheese for two Recipes

pasta , with nooks & crannies for holding the sauce, butter, salt, ground black pepper, onion, chopped finely, flour, milk, sharp cheddar cheese, grated, sharp cheddar cheese, cubed, chives, chopped , mostly for colour, red pepper flakes (optional)

all-purpose flour, low-fat milk, shredded extra-sharp cheddar cheese, divided, light processed cheese, cubed (such as velveeta light), hot cooked macaroni (about 3 cups uncooked ), salt