This is a very rich dish. You'll want to serve it as a side dish, not as a meal. The restaurant uses Black Diamond cheddar cheese that's been aged for five years. It is hard to find.
1 pound elbow macaroni, cooked according to package directions
Recipe
Combine all ingredients except pasta in a large saucepan or Dutch oven and whisk over medium heat until cheese melts and mixture thickens. Add pasta and stir gently to combine. Heat over low heat until heated through.
Serve as is or place on a heat-proof plate and place under the broiler to brown. Makes 10 to 15 servings; about 8 cups.