This is the recipe that I have been using for 40 years. My kids always ask for it on their birthday. I read somewhere that the secret for being a great cook is to add more cheese.
Old-Fashioned Macaroni & Cheese
8 oz. box elbow macaroni
2 tablespoons finely-chopped onion
1 teaspoon salt
¼ teaspoon pepper
3 cups (or more) grated cheese (okay, I've used 4 cups)
2 cups Thin White Sauce
Heat oven to 375 degrees - cook macaroni as directed on package - combine macaroni, onion, salt, pepper and cheese in a two-quart ungreased casserole, stir - pour white sauce over casserole - cover - bake 30 minutes with cover - remove cover - bake 15 more minutes.
Thin White Sauce
2 tablespoons butter or margarine
2 tablespoons flour
½ teaspoon salt
¼ teaspoon pepper
2 cups milk
Melt butter in saucepan over low heat - blend in flour, salt and pepper - cook over low heat, stirring until mixture is smooth and bubbly - remove from heat - stir in milk - heat to boiling, stirring constantly - boil and stir one minute.