Melt chocolate completely in a bowl set over a pan with boiling water, add Coconut oil and salt and mix well.
Combine all peanut butter filling ingredients in a strong blender or food processor until smooth. If necessary, add a little more water to achieve the right consistency.
Fill muffin paper forms into a muffin baking tray. Add about 2 tablespoons of the melted chocolate to each form. Add a teaspoon of the filling on top of the chocolate layer and spread out slightly. Cover the filling with another 2 tablespoons of chocolate and let set in the refrigerator. Peanut Butter Cups can be stored in the fridge for up to 2 weeks.