1. Preheat oven to 350°F (175°C) and butter the baking dish. 2. Prepare the crumble topping by combining flour, cinnamon, ginger, and salt. Toss cold butter cubes in mixture and cut in until pea-sized. Add brown sugar and rub into crumbs; chill in fridge 60 minutes or freeze 30 minutes. 3. Peel and slice apples about 1/8-inch thick. 4. In a bowl, whisk sugar, tapioca flour, cinnamon, ginger, and salt. 5. In a large bowl, combine apples and blackberries, add lemon juice and vanilla, sprinkle in the tapioca-sugar mix, fold gently. Add extra sugar if needed. 6. Spoon fruit mixture evenly into dish, spread crumble topping over, leaving some edges uncovered. 7. Bake 40-45 minutes until juices bubble and topping is golden. 8. Cool 20 minutes before serving. Serve plain, with fresh berries, or vanilla ice cream.