In a deep container, mix the flour and milk over low heat. Mix thoroughly, you can use a whisk to avoid lumps. Do not bring the milk to a boil.
When the milk mixture begins to thicken, add the cream and butter and continue to mix thoroughly until smooth. Add salt, pepper and spices to taste, such as paprika, curry, basil or cumin.
Grate the hard cheese on a coarse grater and add it to the pan with the other ingredients. Stir over low heat until the cheese melts and combines into a single mass with the other ingredients.
Pour the finished sauce into a glass jar and close the lid. Let it cool at room temperature, then put it in the refrigerator for storage. By storing it in a closed jar, you will maintain the tightness and avoid foreign odors getting into the sauce.