In two separate 4-inch deep full steam table pans, combine 2 pouches Macaroni and Cheese, 2 pounds beef, 2 cups chopped onions and half each of mustard and onion powder, if desired.
Cover pans; bake in 350°F convection oven for 30 to 40 minutes or until heated through.
CCP: Heat to 165°F for at least 15 seconds
Remove cover; serve with pickle slices and shredded lettuce, if desired.
CCP: Maintain hot food at 135°F or above