In medium bowl mix together flours, cocoa powder, baking powder, cinnamon, nutmeg, salt, chia seeds and chocolate chips.
On a plate, shallow bowl or plastic cutting board mash banana very well with a fork, until no clumps remain and it’s pretty runny. Add nut butter and vanilla and stir.
Transfer banana mixture to flour mixture and stir until well combined.
Place by heaping tablespoon on cookie sheet and bake 8 minutes. Immediately transfer to cooling rack.