In a large mixing bowl, add the PBfit, water, maple syrup, vanilla extract, salt, and coconut oil, and whisk together until combined.
Add the oat flour and mix well, until a thick dough remains. If the dough is too thick, add a tablespoon or two of water to loosen it up, or if to thin more oat or PBfit. Fold through the chocolate chips.
Transfer the dough to a parchment-lined 8x8 pan and press the dough out evenly. Melt chocolate chips and coconut oil together and spread over the top of the cookie dough. Let chill for at least 1 hour then cut and eat.