Mix all the dry ingredients together in a bowl. Add vinegar, butter and oat milk while your kitchen machine is stirring. Mix until you have a homogenous batter. The batter shouldn`t be runny.
Grease two ramequins with coconut oil. Pour two tablespoons of batter into each ramequin. Place 2-3 dark chocolate pieces onto the batter and filled the ramquins with the remaining batter.
Put in the oven and bake for about 15 minutes.
Serve immediately when still warm and runny inside.