- With the rack in the middle position, preheat the oven to 180°C (350°F). Line two baking sheets with parchment paper.
- In a bowl, combine the flour, baking powder, spices and salt. Set aside.
- In another bowl, cream the butter, brown sugar and molasses with an electric mixer. Add the egg and beat until smooth and creamy. Using a wooden spoon, mix in the dry ingredients and bananas.
- With a spoon, drop 45 ml (3 tablespoons) of dough per cookie on the baking sheets, spacing them 5 cm (2 inches) apart. Sprinkle with sugar if desired. Bake one sheet at a time until the edges of the cookies start to turn brown, about 15 minutes. Let cool before removing from the cookie sheet.