Boil the macaroni according to the boxes directions. I usually do 10 minutes . Cube the Velveeta and grate the the other cheese . Mix the grated cheeses in a bowl and then reserve 1 cup for the topping . Preheat oven to 350 degrees.
Once the noodles are done drain them and set them aside. In the same pot on medium heat melt the butter and add half and half, and evaporated milk . Stir until warm.
Add the Velveeta cheese and stir until melted .
Add the hot cooked macaroni noodles .
Stir in half of the grated cheese from the bowl . Once the cheese is melted remove the pot from the heat.
Beat the egg in a small bowl and temper them . Add a little of the hot mixture to the eggs and beat them . Quickly pour the eggs into the macaroni , stirring quickly,
Spray a 9x13 pan with cooking spray. Add half of the macaroni mixture to the pan.
Spread the other half of the cheese evenly over the macaroni in the dish
Add the remaining macaroni and them top it with the reserved 1 cup of cheese .
Baked in a preheated 350 degree oven for 40-45 minutes .