Fill a standard size muffin/cupcake pan with 12 cupcake liners.
Add the chocolate chips and coconut oil to a microwavable bowl. Heat in 30 second intervals in the microwave until melted, stirring in between.
Spoon 1 tablespoon of the chocolate mixture into the bottom of each of the 12 cupcakes liners.
Place the cupcake pan in the freezer for about 5 minutes, until the chocolate is set.
In a mixing bowl, mix together the peanut butter and powdered sugar until combined into a thick paste.
Spoon approx. 1 tablespoon of the peanut butter mixture on top of each chocolate layer and press it down with your fingers or the back of a small metal spoon so it completely covers the chocolate.
Put the pan back in the freezer for another 5 minutes.
Spoon the rest of the melted chocolate mixture on top of the peanut butter layer, about 1 tablespoon in each cup. *Make sure it’s completely spread out to the edges of the cupcake liner.
Sprinkle the tops with the coarse sea salt, if using.
Put the pan back in the freezer for a final 15 minutes.
Once set, peel the cupcake liners away to reveal your beautifully layered peanut butter cups. They can be stored at room temperature.