The secret to this fruit crumble is to bake the sweet, cinnamon-scented topping separately, to dry it out. Then when you pile those crumbs over a mound of juicy summer fruit, they won’t absorb as much liquid, and stay crisp and cookielike. You can make the crumbs a day ahead. But the crumble is best baked on the day you serve it, preferably while still a little warm and brimming with syrupy fruit. Make sure to taste your fruit before adding the sugar. Sweeter fruit like strawberries, cherries and blueberries need less sugar than tart plums and nectarines. A spoonful of whipped cream or ice cream makes this even better.