Preheat the oven to 350℉/176℃ and line a baking sheet with parchment paper.
Combine the mashed banana, pumpkin puree, maple syrup and vanilla in a large bowl. Then add the dry ingredients (flour, spices, baking powder) and stir until combined.
Use a cookie scoop to scoop balls of the pumpkin cookie dough onto your parchment-lined tray. You should get around 25 cookies. (You may keep the balls round, or press them down if preferred. They won't spread, but taste fluffier when left round.)
Bake the cookies for 14-16 minutes, until lightly golden and firm to the touch, and then remove from the oven.
Let the cookies cool for a few minutes before enjoying, or continue cooling on a wire rack before storing.
Notes
Weigh your flour for the best results. Scooping into a measuring cup can compact the flour and you may end up with more than needed.
Use active baking powder. Baking powder that’s been open in the pantry for several months may lose its effectiveness.
Use very ripe bananas for the best flavour and natural sweetness. The skins should be spotted brown