Fools are traditionally prepared with pureed fruit mixed with whipped cream, or egg custard, or a combination of the two. (The term fool probably comes from the French fouler, meaning to crush. ) They seem to be especially successful when made with sharply flavored garden produce like rhubarb, gooseberries, and black currants, which still have enough bite to be interesting when blended with cream. But strawberries, which are much easier to find, also work quite nicely. Strawberry fool is best when the fruit is mashed rather than pureed, resulting in a more appealing texture. Serve it with cookies.