Preheat oven to 375. Mix filling ingredients in a bowl and place the mixture in a greased 8x8 baking dish. Mix oats, brown sugar, and flour together for topping, cut cold butter into chunks and use a pastry cutter or a fork to add to oat mixture and work into a crumbly texture. Disperse evenly on top of the fruit mixture. Bake 45 minutes or until crisp and golden. Top with whip cream or vanilla ice cream. Yum!