I've always wondered how fool got its name but never bothered to look it up. Perhaps it's because it's so simple a fool could make it? Of course, simplicity and sloppiness should never be confused—the fewer the elements a dish has, the more execution matters. In the case of fool, fruit compote and softly whipped cream are the sole components.
As long as you have access to fresh fruit you can make fool year round—I've made many a berry fool, as well as peach, plum, pear, and even pineapple. There are but two cardinal rules: you must taste the cooked fruit and make sure it's properly sweetened (as Goldilocks might say, it should be neither too sweet nor too sour), and you must never over-whip your cream (remember you'll be mixing it a second time when you fold in the fruit). Heed these, and the world of fool is yours.
For a variation on the method, try making this Peach and Raspberry Fool: Substitute the fruit in the recipe for 2 3/4 cups peaches and 1 cup raspberries, and follow the same method. For an aromatic version, make this Pear, Ginger, and Cardamom Fool: Start with 4 cups roughly chopped pears, 1 teaspoon finely chopped fresh ginger, and 1/8 teaspoon ground fresh cardamom. Cook the pear with the sugar, ginger, and cardamom, and then pass through a sieve. Follow the same method from there.
For a sweet, tropical version, try this Mango and Coconut Fool: Substitute the apple and blackberries for 3 1/2 cups mango, and replace 1/4 cup heavy cream with coconut cream. Otherwise, follow the same method. For a perfectly tart variation, make this Rhubarb and Vanilla Bean Fool: Substitute the apple and blackberries for 4 1/2 cups rhubarb, double the sugar, and scrape 1/2 vanilla bean into the rhubarb before cooking. Follow the same method from there.
Peel, core, and roughly chop the apples and put them in a medium sauté pan with the sugar. Cook the apples over medium-low heat, stirring them every once in a while, until they start to soften. Add the blackberries and continue cooking until the juices release and reabsorb, and the fruit starts to look dry. Remove the pan from the heat and let the apples and blackberries cool.
Pass the cooled fruit through a food mill, or a press it through a fine mesh sieve using the back of a wooden spoon—the goal here is a really smooth puree. Cover and chill in the fridge for at least an hour.
In the meantime, whip the cream in a large bowl until it just holds soft peaks, then cover and chill until the fruit is ready.
Fold a dollop or two of the whipped cream into the chilled apple and blackberry puree. Then scrape the fruit into the bowl with the rest of the cream and continue folding very gently until the two are barely combined. Stop folding before the cream becomes stiff—I find that leaving a few streaks actually looks quite nice. Spoon the fool into 4 glasses and chill for at least 1 hour and up to 3 hours. I like to serve it with some crisp, buttery cookies for contrast.