Combine softened butter, peanut butter & syrup and mix well. Add powdered sugar and mix well. Cover and refrigerate several hours or overnight. You can refrigerate for a couple of days.
Melt some of the chocolate bark. Coat bottom of paper cupcake liners with chocolate. I put a fairly thin coat in bottom using a teaspoon. Allow to harden. I normally do this step and let them set overnight. The harder the chocolate the better. You can acutally line the papers and make the filling in the morning and then finish them that evening.
Melt more chocolate for the tops. Spoon the chilled peanut butter filling into each cup the thickness of a store bought reese cup. Top with enough chocolate to cover the filling and let this harden. I use a tablespoon to put the chocolate on top and then just shake and it will spread over the filling. It doesn't take long for the chocolate to harden but the longer you wait to eat them the better. Remove wrapper when ready to eat.
Note: I coat the bottom rather thin and the top thicker just like the store bought reese cups. You'll get the hang of it.
Extra Note: If I have a little extra melted chocolate left I always chocolate cover pretzels, pecans, raisins, etc.