Yield: 1 pan
Preheat oven to 375°F. Grease an 8 x 8-inch baking dish with 1 Tablespoon of the butter. Set aside.
In food processor, add flour, rolled oats, brown sugar, apple pie spice and salt. Pulse 2 to 3 times to mix. Cut remaining butter (6 Tablespoons) into 1/2-inch cubes and add to flour/oat mixture. Pulse until mixture comes together in small crumbles. Set aside.
In a large bowl, combine peaches and vanilla sugar. Pour into prepared baking dish. Scatter blackberries over top and sprinkle on the crumbly oat mixture.
Bake for 45 minutes, or until bubbly. Serve hot or at room temperature and don't forget the ice cream!