Line a 12-count muffin tin with muffin liners or grease a 12-count silicone muffin tin.
In a microwave safe bowl or stovetop, melt your chocolate and coconut oil.
Spoon out the melted chocolate into the muffin liners and use the back of the spoon to spread the chocolate around the sides. Spoon out tablespoons of peanut butter into the muffin liners, and fill with the remaining chocolate.
Refrigerate the peanut butter cups for at least an hour, for the chocolate to firm up.
TO STORE: These peanut butter cups will keep at room temperature, in a sealed container, for up to 4 weeks. You can store them in the refrigerator if you'd like them to keep longer. TO FREEZE: Place the peanut butter cups in a ziplock bag and store them in the freezer for up to 6 months.