Irish Gumbo asked about the ingredients of a 'rhubarb fool'.
All fools are quite simple (!).
All they are is a mixture of stewed fruit (so, fruit & sugar, cooked and cooled) and whipped cream - either served in layers or gently mixed to retain the appearance of streakiness, pink and white in this case.
You can also get excited and do mixtures in your stewed fruit (add ginger or apple etc).
Some recipes have custard in the mix too.