In a large bowl, combine all dry ingredients - oat flour, protein powder, cocoa powder and optionally chocolate chips. Add the nut butter and maple syrup, then stir well until you get a soft dough, first with a fork and then using your hands. If, after mixing, the dough is still too dry, add some more nut butter, or adjust with more oat flour if it is too sticky. This depends on the type of protein powder that you are using.