Preheat the oven to 350°F. Line a large, rimmed baking sheet with unbleached parchment paper. Put the oats, baking powder, and baking soda into a large bowl and stir with a dry whisk until combined.

Put the bananas, peanut butter, and maple syrup into a medium-sized bowl and stir with a large spoon until combined, leaving some chunky bits of banana. Add the banana mixture to the oat mixture and stir to combine. (The dough will be quite stiff and thick.) Fold in the raisins and chocolate chips.

Drop about 3 tablespoons of the cookie dough onto the prepared sheet and flatten slightly with a rubber spatula. Continue in this manner with the remaining dough. Bake for 20 to 25 minutes, or until the edges are golden brown and cookies are almost set. Transfer the cookies to a wire rack and let cool for 8 to 15 minutes. Stored in an airtight container in the refrigerator, cookies will keep for about 3 days.