Preheat the oven to 180º/356F/Gas4.
Place the sunflower seeds in a food processor bowl and blend until you get a paste-like texture.
Add the cocoa powder, the salt and the vanilla extract, blend again for 1 more minute.
Add the maple syrup, and pulse for 1 minute, then add water and pulse again, stop when you get a very smooth paste.
Transfer to a bowl and sift over the potato flour and baking powder.
Add now the chocolate chips and mix.
Grease a small cake tin with coconut oil and dust with cocoa powder.
Pour the batter into the mould and bake for around 30 minutes. It should be cooked when there's a nice crusty layer on the top.
Let it cool down completely before slicing.