This pie filling calls for tapioca flour. If you can’t find this, try using extra cornstarch or some flour as a replacement thickener.
1kg blueberries (2 pounds)
1 cup sugar
¼ cup tapioca flour
2 tbsp cornstarch
pinch of salt
FOR THE CRUMBLE TOPPING
1½ cups plain flour
125g cold unsalted butter, cubed (1/2 cup + 1 tbsp)
3 tbsp brown sugar
pinch of salt
Method
Preheat the oven to 180 C (350 F) and line a 9 x 13 inch pan with baking paper.
To make the crust, sift the icing sugar into the bowl of your stand mixer. Add the flour and salt. Fit the mixer with the paddle attachment and mix on a low speed to combine.
Add the butter and mix on a low speed just until a dough forms.
Put the dough in the pan and press it evenly into the base and up the sides. This will take a little time and is annoying, but keep at it.
Line the crust with parchment paper and fill with pie weights or dried beans. Bake the crust about 25 – 35 minutes, until it evenly colours to a deep golden brown. I had to uncover mine for the last 5 minutes.
While the crust is baking, make the crumble. In the same stand mixer, add the flour, butter, sugar and salt. Mix on a low speed for 4 - 5 minutes, until a buttery crumble forms. Set aside.
To make the filling, mix together the blueberries, sugar, tapioca flour, cornstarch and salt in a large bowl. Set aside.
When the crust is ready, take it out of the oven. Spread the blueberry filling evenly over it, and top with the crumble.
Return to the oven and bake for 40 minutes, until the crumble is golden brown. Allow to cool completely before cutting. Makes 20 pie bars.
Recipe by Butter Baking at https://www.butterbaking.com/2012/09/26/blueberry-crumble-pie-bars/