If using apples, select tart, crisp ones to balance the sweetness of the topping. Gravenstein, Pippin, and Braeburn are all good choices.
Preheat the oven to 375°F. Have ready an unbuttered 2-inch-deep 2-quart baking dish.
Peel, core, and cut into 1-inch chunks:
Or use the same amount of:
Spread the fruit evenly in the baking dish and toss with:
Combine in a medium bowl or food processor:
Add:
Cut in the butter or pulse until the mixture resembles coarse bread crumbs. If desired, stir in:
Scatter the topping evenly over the fruit. Bake until the topping is golden brown, the juices are bubbling, and the apples are tender, 50 to 55 minutes (start checking at 40 minutes if using a tender fruit). Serve hot or at room temperature.