Preheat convection oven to 350°F or conventional oven to 400°F.
Combine topping ingredients in a separate bowl and set aside.
In large stock pot, combine all ingredients except elbow macaroni and topping ingredients. Heat over medium heat. Stir frequently to prevent scorching.
CCP: Heat to 165°F for at least 15 seconds
Add macaroni to sauce, mix together.
Spray two half steam table pans with nonstick spray and portion macaroni and cheese evenly into two pans.
Sprinkle 2 to 3 tablespoons of topping mixture on top of each pan.
Bake in convection oven set at 350°F uncovered for 15 to 20 minutes, or conventional oven set at 400°F uncovered for 25 to 30 minutes until internal temperature reaches 165°F and cheese is melted and edges are slightly brown.