Set out 10 standard or 20 mini cupcake liners on a small baking sheet.
Melt half of the chocolate with the half of the coconut oil in a double boiler (or you may use a microwave). Divide this melted chocolate mixture evenly among the prepared cupcake liners, and spread evenly. Place in the fridge or freezer for 10-15 minutes, until the chocolate has solidified.
Meanwhile, mix the peanut butter with the maple syrup until smooth. Remove the hardened chocolate from the freezer, and divide the peanut butter filling among the cups. Place back in the fridge or freezer for a few minutes to firm up, then press down the peanut butter to spread it evenly inside each cup.
Melt the remaining chocolate and coconut oil, then divide evenly among the prepared cups. Sprinkle the tops with a bit of sea salt if desired, and place in the fridge or freezer for another 20-30 minutes to solidify.
Allow to sit at room temperature for a few minutes before serving. You may store these cups in an airtight container in the refrigerator for up to 5 days, but I doubt that they will last that long!