In a saucepan, melt the butter over medium heat.

Once the butter is melted, add the plain flour to the saucepan. Stir constantly to form a smooth paste, cooking for about 1-2 minutes. This mixture is called a roux and will act as a thickening agent for the sauce.

Slowly pour the milk into the saucepan while continuously stirring to prevent lumps from forming. Keep stirring until the mixture is smooth and thickened, usually about 3-5 minutes.

Once the sauce has thickened, add the salt and cayenne pepper. Adjust the seasoning according to your taste preferences.

Gradually add the grated cheddar cheese to the sauce, stirring constantly until the cheese is fully melted and the sauce is smooth and creamy. This usually takes a few minutes.

Once the cheese sauce reaches the desired consistency and flavor, remove it from the heat. It’s now ready to be served with your favorite nachos or other snacks!