Preheat the oven to 350 degrees and grease a small baking dish with cooking spray/oil/butter and set aside. In a small mixing bowl, coat the blueberries with lemon juice, mix well then transfer to the baking dish and spread out evenly. In a separate mixing bowl, combine the almond flour, coconut flour, granulated sweetener of choice, protein powder and cinnamon and mix well. Melt your nut butter with your maple syrup and add to the dry mixture. Stir until a crumbly texture remains. Cover the blueberries with the 'crumble' mixture and bake for 12-15 minutes, or until the crumble is golden brown. Allow to cool for 5 minutes in pan before serving or allow to cool completely before refrigerating.