Add the dark chocolate chips and 1 teaspoon coconut oil to a microwave-safe bowl or a double boiler. Melt gently until smooth, stirring often. Be sure no tiny droplets of water get into the chocolate, or it can seize.
Using a spoon or pastry brush, coat the bottom and halfway up the sides of your silicone heart mold with melted chocolate. This chocolate shell is what gives the peanut butter cup hearts their structure.
Place the mold on a large baking sheet and freeze for about 10 minutes, or until the chocolate is completely solid.
In a medium bowl, combine peanut butter, honey, and melted coconut oil. Stir until smooth and creamy. The peanut butter filling should be soft but not runny – similar to peanut butter dough.
Remove the mold from the freezer and spoon the peanut butter mixture into the center of each heart, leaving a little space at the top for the final chocolate layer. Gently tap the baking sheet to help the filling settle into the exact spot.
If the remaining melted chocolate has cooled, gently rewarm it. Spoon chocolate over the top of each heart, fully covering the peanut butter filling. Smooth the top part of the hearts with the back of a spoon.
Return the mold to the freezer and chill until the hearts are fully set, about 20–30 minutes. Once solid, gently pop them out of the mold.