You’ll learn everything you need to know about Mac and Cheese roux in this ultimate guide. The classic roux is made with two ingredients: flour and butter. It is a thickener used to thicken sauces such as bechamel and cheese sauce. And there you have it! A delicious and creamy roux-based macaroni and cheese that is sure to please the entire family. Finally, add the cooked macaroni to the cheese sauce and stir until everything is evenly mixed. Stir until the cheese is completely melted and the mixture is smooth. At this point, you will need to add the shredded cheese to the mixture. Once all of the milk has been added, continue to cook the mixture over medium heat, stirring constantly, until it comes to a boil. Slowly add the milk to the roux, whisking continually until the mixture is smooth. Next, increase the heat to medium and cook the roux, stirring constantly, for about 2 minutes. Once the butter has melted, add the flour and whisk until the mixture is smooth. First, melt the butter in a saucepan over low heat. Here is a step-by-step guide on how to make a roux for macaroni and cheese. While it may seem like a daunting task, making a roux is actually quite simple. But what exactly is a roux? A roux is a mixture of flour and fat (usually butter) that is used to thicken sauces, stews, and soups. When it comes to macaroni and cheese, there is no denying that a roux is a key ingredient.