Cook macaroni not too cook (remember your macaroni is still cooking in the oven) don't want to over cook

Sauce on very low heat add heavy cream half and half milk regular milk a drop of lemon juice (lemon juice is optional just keeps the cheese from curling up) once it starts to boil add cheese but save some for topping I add flour or starch to thicken pour over Mac top with cheese place in oven for 30 minutes or until your liking