Preheat the oven to 350 degrees Fahrenheit.
In a large mixing bowl, whisk together the baking powder, salt, cinnamon, oats and almond flour.
Add in all remaining ingredients and use a fork to mash the butter or oil into all ingredients.
The dough shouldn't be too wet, but it should be dry either, so keep mixing until the wet ingredients are well incorporated.
Add about 2/3 of the dough to an 8x8 pan lined with parchment paper. Press down firmly with your hands. I suggest lining the pan going both ways, it makes for much easier removal!
Bake for 10 minutes and set aside the remaining dough.
While baking, add the blueberries, lemon juice and maple syrup to a pot on the stove. Heat over low heat until the blueberries start to melt and bubble.
Whisk in the starch and let simmer for about 2 minutes to allow it to thicken.
Remove from heat.
When the crust is done baking, remove from the oven and let cool for 5 minutes.
Add the blueberry mixture to the crust and crumble on the remaining dough on top.
Bake, uncovered, for 25-30 minutes or until the crust is golden brown.
Remove from the oven and let cool for at least 1 hour before slicing. It will get pretty messy if you slice when they're still warm! I slice into 16 squares, but you can also do 9 or 12!