For the bottom layer: Spray a 9X9-inch casserole dish with cooking spray. Toss together all bottom-layer ingredients in large bowl. Place the mixture into the casserole dish.
To make the topping: Whisk together flour, sugar, baking powder and salt in a bowl. Cut or rub shortening into flour until it resembles coarse meal. Stir in milk. Dot pieces of dough over fruit mixture.