From America's Test Kitchen Season 11: Sweet Endings
Traditionally, fruit fool is made by folding pureed stewed fruit (traditionally gooseberries) into sweet custard. Modern fool recipes skip the traditional custard and use whipped cream. But whipped cream blunts the fruit flavor and is too light and insubstantial—or, worse, it can turn the dessert soupy. We wanted a dessert with intense fruitiness and rich body—and we wanted to use raspberries or strawberries rather than the traditional gooseberries.
Gooseberries are naturally high in pectin—when exposed to heat, sugar, and acid, pectin breaks down and causes fruit to thicken, which made them ideal for fruit fool. We wanted to use raspberries and strawberries, which are low in pectin, so our first challenge was to thicken the fruit properly. We turned to gelatin to thicken our berries, but used a judicious hand (just 2 teaspoons), softening the gelatin in some uncooked berry puree, and then combined the softened mixture with some heated puree to help melt and distribute the gelatin. The result? A smooth, thickened puree with intense fruit flavor.
Now we just needed a richer, sturdier cream base to partner with the fruit puree. We liked the ease of using whipped cream rather than custard, so why not make whipped cream more custard-like? Combined with sour cream, the mixture was airy yet substantial, and the sour cream added just the right touch of richness, along with a tangy undertone. For even more fruit flavor, we layered the fruit puree and cream base with fresh berries that had been macerated in sugar to release excess juice. Finally, topping the dessert with crumbled sweet wheat crackers added a pleasant, nutty contrast.
Blueberries or blackberries can be substituted for raspberries in this recipe. You may also substitute frozen fruit for fresh, but there will be a slight compromise in texture. If using frozen fruit, reduce the amount of sugar in the puree by 1 tablespoon. The thickened fruit puree can be made up to 4 hours in advance; just make sure to whisk it well in step 4 to break up any clumps before combining it with the whipped cream. For the best results, chill your beater and bowl before whipping the cream. We like the granular texture and nutty flavor of Carr’s Whole Wheat Crackers, but graham crackers or gingersnaps will also work.