Mix up the egg and banana (and cocoa or cinnamon) with a stick blender or small blender until well combined and fluffy (or if you don't have that, use a fork to squash the banana in the egg and give a good whisk).
Heat a non-stick frying pan, with a small brush of oil or butter if it needs a bit of lubrication.
Once hot, pour in a tablespoon of the batter to make a stack of small pancakes (don't overfill the pan so that you can more easily flip) or all of the mixture to make one large pancake.
Gently cook through until holes appear in the surface and the batter is starting to set (about 3 mins).
Carefully flip over with a turner or by sliding onto a plate to flip. Cook the second side for a couple of minutes.
Serve with the warm berries and quark in a stack or folded in half.