Preheat oven to 350 degrees Fahrenheit.

To prepare the blueberry filling, add the blueberries, maple syrup, and lemon juice to a small pot over medium high heat. Bring the mixture to a simmer for 5 minutes while stirring the mixture and allowing the blueberries to break down. Add the chia seeds and stir to combine. Reduce heat to low and gently simmer for 10 minutes, stirring occasionally. Set aside.

To prepare the cumble, add the almond flour, oats, baking powder, cinnamon, and nutmeg to a large bowl. Stir until combined. Add the dates and water to a small blender. Blend on high until a smooth date paste is formed. Add the date paste, almond butter, maple syrup, melted coconut oil, and vanilla to the bowl. Stir until fully combined and crumbly.

Line a 9x9 baking dish with parchment paper or grease with coconut oil. Divide the batter and press 2/3 of the batter into the prepared baking dish. Save the remaining 1/3 of the batter for the topping.

Pour the prepared blueberry filling over the base and spread until it evenly covers the base. Crumble the remaining 1/3 of the batter over the blueberry filling.

Bake in the prepared oven for 24-26 minutes, until the crumble topping is slightly golden. Let cool and then cut into 16 bars. Store leftovers in the fridge and warm them slightly before serving.