Whisk together the oats, flour, baking powder, cinnamon, and salt in a small bowl. In a separate larger bowl, mix together the butter, mashed banana, and vanilla. Stir in the maple syrup. Then, add in the dry ingredients, stirring just until just blended. Fold in the blueberries and dark chocolate chips, saving some for the top if desired. Put the cookie dough in the fridge for 20-25 minutes.