It's lots of butter and is the basis of any Cheese Sauce, Parsely Sauce, or . . . you get the idea
It's simple but you can cock it up if you try to rush it. But then it only takes a couple of minutes anyway so why mess around? this makes about half a pint but you just increase each of the ingredients in this proportion. the important bit s that you have equal amounts (weight) of butter and flour
Melt the butter in the pan and add the flour. Cook it for a couple of minutes until you get a beige blob and can't see any white flour left in the pan.
Add a splash of milk and combine it. Keep splashing milk in and mixing until you get a smooth paste, then you can be less careful - add bigger splashes of milk (or even all that's left.
Whisk it over a fairly high heat (you want it bubbling) for a few minutes until it's smooth and shiny
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