In a bowl, whisk together flour, banana powder, cocoa, baking powder, and salt.In another bowl, mix sugar, brown sugar, oil, eggs, and vanilla until combined.
Add the dry ingredients to the wet and stir until a dough forms. Chill the dough for at least 1 hour (it will be sticky). Preheat the oven to 350°F (175°C).
Scoop dough into small balls and roll them in powdered sugar until coated.
Place on a lined baking sheet and bake for 10–12 minutes. Let cool — they will have a soft center and a beautiful crackled top.
Image for illustrative purposes only. Final presentation may vary.
CHEF'S TIP
Chill the dough for 15–20 minutes before rolling to keep the cookies from spreading too much.