Line a 12-cup muffin tin with paper liners. In a microwave-safe bowl, combine the sugar-free chocolate chips and coconut oil. Microwave in 20-second intervals, stirring between each, until completely melted and smooth.
Spoon about 1 teaspoon of melted chocolate into the bottom of each liner. Use the back of the spoon to spread it into an even layer across the bottom. Place the muffin tin in the freezer for 10 minutes to set the chocolate.
While the chocolate layer firms up, prepare the filling. In a bowl, stir together the peanut butter, powdered erythritol, coconut flour, and sea salt until a thick, slightly crumbly dough forms.
Roll the peanut butter mixture into 12 small balls, then flatten each one into a disc that fits inside the liners. Place a disc on top of each set chocolate layer and press down gently.
Spoon the remaining melted chocolate over each peanut butter disc, spreading it to the edges so the filling is fully covered. Tap the muffin tin lightly on the counter to smooth the tops.
Freeze for at least 20 minutes until the chocolate is completely set. Remove from the freezer about 5 minutes before serving so the filling softens slightly. Store any extras in the refrigerator.
