Preheat the oven to 180°C and line a small baking tin (about 20 x 20 cm) with parchment paper.

Add the chickpeas, banana, peanut butter, milk, honey (or maple syrup), and vanilla extract (if using) to a blender or food processor. Blend until completely smooth, scraping down the sides as needed.

Transfer the mixture to a bowl. Stir in the oat flour, baking powder, and salt until fully combined. Fold in the chocolate chips if using.

Spoon the batter into the prepared baking tin and smooth out the top.

Bake for 30 minutes, or until the edges are set but the centre still looks slightly underbaked.

Allow to cool completely in the tin before slicing into bars.