Preheat oven to 375°F. Prepare a 10 x 15 inch baking dish.
In a large bowl, combine flour, sugar, oats, baking powder and cinnamon.
Crumble chilled butter into flour mixture with hands (you can also use a pastry cutter) until mixture resembles coarse crumbs or pea sized butter bits.
Stir 1/2 cup of flour mixture into cooled zucchini mixture.
Press half of remaining butter & flour mixture into the bottom of prepared pan and bake for 10 minutes.
Carefully remove from oven and spread zucchini mixture over top of crust and sprinkle remaining butter mixture over zucchini.
Bake for 35-45 minutes or until top is golden brown.
Serve hot with ice cream or whipped topping.