This mac and cheese is super creamy, thanks to a secret ingredient! Can you guess what it is?
Carefully add macaroni to saucepan and reduce heat to medium-low. Cook, stirring occasionally with wooden spoon, until macaroni is soft, about 7 minutes.
While macaroni is cooking, tear American cheese slices into small pieces. When macaroni is soft, add American cheese pieces and mustard to saucepan and cook, stirring constantly, until cheese is completely melted, about 1 minute. Turn off heat.