Stir together dry ingredients in a medium bowl. Blend in butter with your fingertips, fork, or pastry blender until mixture forms pea-size clumps. Spoon topping evenly over fruit filling of your choice and bake on a middle rack in a preheated 375 degree F oven until fruit is bubbling and the top is nicely browned, about 60 minutes. Let the crumble cool for about 10 minutes before serving.
Recipe courtesy of Corky Pollan