Preheat oven to 170degC. Line a baking tray with baking paper.
Pat chickpeas dry with paper towels. Place in the food processor with nut butter, vanilla, brown sugar, baking powder, ground almonds, and butter or coconut oil. Blitz until all ingredients are well combined and have formed a cookie dough consistency.
Add dark chocolate and pulse briefly to distribute the chocolate throughout the cookie dough.
Roll heaped tablespoonfuls of cookie dough into balls (having wet hands helps stop the dough from being too sticky to roll) and place on prepared baking tray, about 3cm apart (they won’t spread much). Flatten slightly with the back of a wet fork.
Bake for 12-15 minutes until lightly golden. Remove from oven and leave cookies to cool slightly. Use a fish slice to transfer them carefully to a wire rack to cool completely – they will be quite delicate.
These cookies are lovely eaten warm, but can be stored in an airtight container in the pantry for up to a week, or frozen for several weeks – when you want to eat one (or two!) just warm for 10 seconds in the microwave and the chocolate will melt and go gooey.