Blend together 3 heaping tablespoons white
flour and 1 cup milk (I use a
small wisk). Cook over medium heat, stirring constantly until thick. Let
cool. Meanwhile cream 1 cup of butter, 1 cup of regular sugar, 1 tsp
vanilla. When the flour mixture is cool, add it to the butter/sugar mixture
and beat with electric mixer until thick and fluffy.
If the flour mixture isn't pretty well cooled off, it melts the butter when
you combine them, and then it never really gets thick - though it still
tastes good. On the other hand, if you let the flour mixture set for a long
time, then it can come out kind of lumpy. So, you want to aim for cool, but
not hardening.
Enough for a two layer 8-9" cake.