1. Preheat oven to 350 degrees Fahrenheit. Line an eight-inch pan with Gefen Parchment Paper and generously spray with nonstick cooking spray. Set aside.
2. For the crust and crumble: In a large bowl, mix oat flour, oats, brown sugar, cinnamon, baking soda and salt. Add melted butter, vanilla extract, and almond extract and stir until a nice crumble forms and dough begins to clump together.
3. Measure one and three-fourth cups of the mixture and press into the prepared pan to form a crust. Refrigerate remaining crumble. Bake crust for six minutes. Let cool slightly.
4. For the filling: Mix blueberries, maple syrup, dissolved cornstarch, cinnamon, almond extract, lemon zest, and salt in a medium saucepan over medium heat. Use a wooden spoon to press down and break down the blueberries just a bit. Bring to a boil, then reduce heat and cook for four to five minutes until mixture is slightly thickened and coats the back of a spoon.
5. Pour mixture over cooled crust and spread gently.
6. Sprinkle remaining topping over the blueberry filling. Bake for 25 to 30 minutes or until filling is bubbly and top is lightly browned.
7. Allow bars to cool completely on a wire rack before transferring to the fridge to chill. Cut bars when cold.