Place cooked macaroni in slow cooker and add butter. Stir until butter is melted.
Add evaporated and whole milk, parmesan, romano, cheddar cheese, nutmeg, and salt and pepper. Stir well.
Cover and cook on low for 3 hours. Stir well and sprinkle with parmesan and another dash of nutmeg, and serve hot.Tip: If you don’t have a slow cooker, put pasta, milk and cheeses in a large baking dish and bake for 50 minutes at 350º F.