Line a standard muffin tin with paper or silicone liners.
Create a double boiler by placing a heatproof bowl over a saucepan of simmering water.
Add the chopped dark chocolate and coconut oil to the bowl, stirring occasionally until completely melted and smooth.
Spoon about 1 tablespoon (15 ml / 0.5 fl oz) of the melted chocolate mixture into the bottom of each muffin liner, just enough to cover the base.
Place the tin in the freezer for 10-15 minutes, or until the chocolate is firm.
While the chocolate base chills, prepare the filling.
In a separate medium bowl, whisk together the unsweetened peanut butter, raw honey, and sea salt until well combined and smooth.
Remove the muffin tin from the freezer. Spoon about 1-2 teaspoons (10 ml / 0.3 fl oz) of the peanut butter mixture onto the center of each hardened chocolate base.
Carefully pour the remaining melted chocolate over the peanut butter layer, ensuring it's fully covered.
Place the muffin tin in the refrigerator for at least 2 hours, or until the cups are completely firm. Store in an airtight container in the refrigerator.
Sprinkle a pinch of flaky sea salt on top of the final chocolate layer before refrigerating for a gourmet touch and a delightful flavor contrast.