Blueberry Crumble Bars

-1 Preheat the oven to 350°F.
-1 In a large bowl, combine all the crust ingredients. Mix until well incorporated. It should be slightly crumbly. 
-1 In a parchment lined 8 x 8 or 9 x 5 baking dish, press down ⅔ of the oat mixture to create the crust. Reserve the rest for the crumble.
-1 Bake the crust for 10 minutes while you prep the filling. Once done, remove from oven and set aside until filling mixture is ready. 
-1 In a medium saucepan, pour in the blueberries over medium heat. Bring to a boil, stirring every few minutes.
-1 Once the berries start to bubble, lower the heat and mix in the lemon juice and maple syrup.
-1 Using a spatula or wooden spoon, gently mash the berries. You can leave some berries whole or in pieces if desired. 
-1 Let simmer for 10-15 minutes, stirring occasionally. 
-1 Add the vanilla extract and tapioca flour to the blueberries, starting with a tsp at a time. Let the mixture simmer for another 5 minutes until thick. 
-1 Pour the filling on top of the baked crust. Crumble the rest of the oat mixture over the filling. 
-1 Bake for an additional 20-25 minutes, until the crumble is golden.
-1 Let cool for 10 minutes before slicing into bars.
-1 Keep stored in refrigerator for up to two weeks.