In a mixing bowl, combine:
Add 80-100ml chickpea water (aquafaba), enough to bind all the ingredients together and produce a sticky cookie dough.
Coarsely chop 100g pistachios and set aside.
Divide the dough into 28 equally sized pieces (each cookie weighs 25g). Roll each portion of dough between the palms of your hands and then lightly press into chopped pistachios to coat on both sides.
Preheat the oven to 175° C / 350° F / GM 4. Place the cookies on a parchment-lined baking tray. Bake for 15-20 minutes, until they are lightly browned on top. Remove from the oven and let the cookies cool down before transferring to a plate (or else they may fall apart).
Modified from Lazy Cat Kitchen