Cheese Sauce

When you're ready to make the sauce, put the milk in a saucepan.

Then simply add the sauce flour, butter and seasoning and bring everything gradually up to simmering point over a medium heat, whisking continuously with a balloon whisk, until the sauce has thickened and becomes smooth and glossy. Then turn the heat down to its lowest possible setting and let the sauce cook very gently for 5 minutes to take the raw taste out of the flour, stirring from time to time. After that stir in the cheddar and grated parmesan.

Finally taste and check for seasoning.