Pre-heat your oven to 350 degrees.
Stir the dry crumble ingredients in a medium bowl with a fork, then stir in the melted butter. Use your hands to finish mixing and keeping the large crumbles intact. Be careful not to over-mix and turn the crumble to dust.
Grease a 7x10x5" baking dish (or pie dish) with butter wrapper or cooking spray.
Place a layer of crumble on the bottom and sides, saving enough for the top (the most important part).
Add filling, then sprinkle the remaining crumble on top.
Bake for 30 to 45 minutes, or until the crumble turns golden.
Let cool and serve with ice cream or whipped cream.