Take a small amount of chocolate and place it in the bowls. Melt the chocolate in the microwave on high, in bursts of 30 seconds, stirring in between each burst. Or use the double boiler method on the stovetop burner.
Add some chocolate to the mold each bottom half. You can leave it just on the bottom or also tilt the mold and rotate it so the whole bottom half inside gets covered. You can do the same with the top half but you will need to plug the hole in the top. Allow the chocolate to set for 15 to 20 minutes.
Combine the peanut butter, powdered sugar, salt, and then melt your butter (microwave 20 to 30 seconds) and pour that in. Mix well until a dough forms. It shouldn't be sticky, if it is, add a little bit more powdered sugar.
Take a large chunk of the peanut butter mixture and roll it into a ball so it will fit inside the mold. The larger it is the thinner the walls of chocolate will be. Add the ball to the bottom of the mold.
You can use a piping bag and pipe chocolate around the ball on the bottom half right now if you like. Place the top part of the mold on. Then use a funnel and add chocolate so it fills up the mold. The funnel isn't the best. Use a piping bag and pipe chocolate through the hole so it fills up any gaps.
Chill the molds in the fridge or freezer for at least one hour, the chocolate needs to get nice and firm. Then you can pull them apart and take out the awesome Star Wars Death Star Peanut butter cup. Enjoy!