Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or lightly grease it.
In a large mixing bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy. Beat in the egg and vanilla extract. Stir in the mashed banana.
In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the nuts, chocolate chips, and raisins.
Scoop the dough by rounded tablespoons onto the prepared baking sheet, spacing them about 2 inches apart.
Bake for 12-15 minutes, or until the cookies are lightly golden and set. Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.
Once the cookies are completely cooled, dust them with powdered sugar. Serve with a glass of milk, if desired.
