The easiest recipe I know is from the new Joy of Cooking -- its part of the Fettuccini Alfredo recipe. It is heat 1 cup of heavy cream and 1 cup of Parmesan cheese. I then toss in cooked noodles (or tortellini or ...) and some cooked chicken -- yummy.
My DSIL can't have anything with gluten so I make this -- usually double or triple the recipe.