Sometimes there are things that my daughter wants to eat that are very difficult for me to resist. I chew gum. I chew gum until the food is cooked, served, and put away. That way there is no "just one bite" of anything.
Macaroni and cheese + mint gum = gross
Another option is to try to quell that kind of craving in a way that works for you so that you don't feel deprived and have such a temptation. Instead of mixing your cheese sauce with macaroni, make it with chopped cauliflower pieces. You can even bake it just like a baked macaroni or eat it "stovetop."