To make macaroni and cheese from scratch, you’ll need to start by making a roux. A roux is a mixture of equal parts flour and fat that is used to thicken sauces, soups and stews. For macaroni and cheese, we use butter as the fat component and make a light-colored (blond) roux.
When the roux has reached the right color and consistency, warm milk is whisked in to create a thickened white sauce called béchamel. When the béchamel sauce has reached the right consistency, it’s time to stir in the cheese.
Once all the cheese has melted and the sauce is smooth and creamy, it’s ready for the pasta and any other ingredients you might be adding. If your recipe is for a stovetop mac and cheese, you can serve right away, whereas a baked mac and cheese needs a little time in the oven before serving.