Make the Muffin Batter: Mash your bananas in a large mixing bowl using a fork, until there are no lumps. Add the maple syrup, eggs, milk, and vanilla to the mashed bananas and whisk together until combined. Add the dry ingredients - the oat flour, whole oats, baking powder and soda, salt, and cocoa powder. Whisk until well combined. Stir in the chocolate chunks last.
2 large overripe bananas, 1/3 cup maple syrup, 2 large eggs, 3/4 cup milk, 1 tsp vanilla extract, 2 tsp baking powder, 1/2 tsp baking soda, pinch of salt, 1/4 cup cocoa powder, 1 cup chocolate chunks, 2 and 1/4 cups whole rolled oats, divided