Preheat oven to 375 degrees F.
In a large mixing bowl, combine blackberries, prepared apples, white sugar and cornstarch. Spread into a 9 x 9 (2 quart) baking dish.
In another large mixing bowl, add the flour, oats, dark brown sugar, cinnamon, nutmeg and coconut flakes. Using a pastry cutter or your fingertips, cut in the butter until the mixture is crumbly.
Bake 30-35 minutes in the preheated oven. When it's done, allow to cool before serving. Top with ice cream and more coconut flakes if you wish, enjoy!