Bring a large pot of water to a boil, add salt and macaroni and cook for 4 to 5 minutes (until the macaroni is half cooked). Butter a 3-quart baking dish, add 1/3 of the cooked macaroni and then layer with cheese, salt, and pepper; repeat this until the elbows have all transferred. Pour the milk and heavy cream over the macaroni. Cover the macaroni and cheese with tinfoil and bake for 1 hour and 15 minutes. Remove the foil and bake for an additional 10 minutes or until the macaroni is brown and bubbling on top.