This crumble is best the day it’s made, but leftovers keep, refrigerated airtight, for 3 days and make a great breakfast with a scoop of yogurt. If you prefer dairy butter, use an equal amount of cold unsalted butter and increase the salt in the crumble to 1/2 teaspoon.
Evenly crumble the topping over the baked fruit, keeping some pieces in hazelnut-size chunks. Bake until the fruit is bubbling vigorously and the topping is a deep golden brown, 25 to 35 minutes. Let cool slightly. Serve warm with ice cream.