Prepare the topping: In a food processor, pulse the flour and butter until the texture of coarse cornmeal. Remove to a bowl and toss with remaining ingredients until mixed. (This can be refrigerated for 1 week or frozen for 6 months.)
Preheat the oven to 350 degrees. Butter a 10 by 8-inch casserole dish.
Prepare fruit filling: Combine all ingredients in a bowl and mix well. To assemble: Place the fruit filling in the buttered dish. Cover the filling with a 3/4-inch layer (or more) of the topping.
Bake until bubbling and the fruit in the middle is tender, 25 to 30 minutes. Serve warm for best flavor. Serve with ice cream, if desired.