• Before you start this recipe make note that you will need to refrigerate the crumble for about an hour or freeze it for 30 minutes.

Streusel Topping

• Cut the cold butter into 1/2-inch cubes and place it back in the refrigerator so it stays cold while you prepare the other ingredients.
• Place the flour, cinnamon, ginger and salt in a medium size bowl. Whisk until well combined. Add the butter to the dry ingredients and toss the butter into the flour mixture with your hands until all the butter is well coated.
• Use the pastry blender to cut the butter into the flour mixture, until the butter is the size lima beans. You can also you use your hands if you don’t have a pastry blender. To mix it with your hands take each piece of butter and smash it flat between your index finger and thumb. Continue to do this until the butter is broken up and size of lima beans
• Add the brown sugar and use your hands to rub the sugar into the butter-flour mixture. The mixture should be crumbly and look like large bread crumbs. Refrigerate the crumble for 60 minutes or place it in the freezer for 30 minutes.
• The crumble can be made up to one week in advance and refrigerated until ready to use.

Apple Blackberry Filling

• Preheat the oven to 350°F. Butter the baking dish.
• Whisk together the granulated sugar, tapioca flour, cinnamon, ginger, and salt in a small bowl and set aside.
• Peel the apples.  With the apples in the upright position and the stem pointing skyward, cut down and around the cores to remove the flesh in 4 lobes (you’ll be left with a square-shaped core).  Set the lobes flat-side down and slice the apple lengthwise into 1/8-inch slices, making them as even as possible. 
• Taste the apples and blackberries before adding the additional ingredients. The sugar called for in the recipe should be enough if the blackberries are sweet. If they are a little tart, you may want to add about 2-3 tablespoons of additional sugar.
• Place the apples and blackberries in a large bowl. Add the lemon juice and vanilla extract to the fruit. Sprinkle the tapioca-sugar mixture over the fruit and gently fold the dry ingredients into the apples and blackberries. Taste the mixture. If the fruit mixture isn’t sweet enough add 2 more tablespoons of sugar and taste again.
• Spoon the fruit into the prepared baking dish and use the back of the spoon to make an even layer. Spread the crumble over the apples and blackberries. Leave the edges a little exposed so you can see the fruit juices bubbling up as they crumble bakes.

Bake the Apple Blackberry Crumble

• Bake the crumble for 40-45 minutes or until you see the fruit juices rapidly bubbling up all the way around the baking dish and a little towards the center. The syrup will be thick, dark, shiny, and clear.
• Remove the crumble from the oven, set it on a wire rack to cool at least 20 minutes to allow the juices to set up. It will still be warm.
• Serve it plain, with fresh blackberries, or with a scoop vanilla ice cream.

How to Store the Crumble

• The crumble can be stored at room temperature for 1 day unless it is very warm in your house (over 75 degrees F). In that case I recommend storing it in the refrigerator at the end of day covered with plastic wrap or foil. The crumble is good in the refrigerator for up to 3 days.
• To store the crumble in the refrigerator let it cool completely before covering tightly with plastic wrap or foil.
• Reheat the refrigerated apple blackberry crumble in a 350°F (180°C) oven for 15-20 minutes uncovered.