This is a fantastically easy cake to make, and the best bits about are a) that it is gluten & dairy free, and b) that it has no added fat!
Put the chickpeas in a food processor and blitz until a roughish paste. Add the eggs, the sugar, the zest of the lemon and the juice of half the lemon. Blitz to make a smooth batter. Pour immediately into a greased and lined 2lb loaf tin, and bake in a medium oven (160C) for 35 - 45 minutes, until risen, firm to the touch, and golden brown. Take out of the oven, and leave to cool for 15 minutes, then pour over the juice of the rest of your lemon, and some honey if you like, and wait until cooled completely before removing.
This does keep well (if it lasts that long), but doesn't freeze.