Preheat the oven to 350 degrees.  Line two baking sheets with parchment or Silpat mats.  Set aside.

In the bowl of a stand mixer or a mixing bowl, beat together the butter, peanut butter, brown sugar, and granulated sugar until fluffy and fully combined.  Scrape down the sides of the bowl with a spatula. Add in the egg and vanilla extract. Beat the mixture until creamy.

In a small bowl, stir together the flour, baking powder, baking soda, and salt.

Add the dry ingredients to the peanut butter mixture and with the mixer on low speed, mix in the dry ingredients until fully combined.

Use a tablespoonful of dough, roll into 24 balls.  Place twelve balls on each prepared baking sheet.

Using the back of a pestle or end of a lemon reamer, make an indentation in each of the balls, but do not flatten completely.

Bake in the oven for 10 minutes.  Remove the pans from the oven and use the same tool to make the same indentation.  Return to the oven and bake for another 10 minutes or until lightly browned.

Remove pans from the oven.  If any of the cookies puffed up and lost the indentation, use the tool to reshape the cookie.

Allow the cookies to cool completely.

Remove the wrappers from the round chocolate truffles.  Set aside.

In a glass measuring cup, add the chocolate chips and shortening.  Microwave, at half power, in 30-second increments. Stir and microwave until melted, stirring after each 30-second increment.

Use a small spoon to drop a very small dollop in each of the indentations in the cookies.  Lay a truffle on top and push down gently.

Spoon the remaining melted chocolate into a small ziplock bag.  Cut the tiniest bit off of one corner. We are going to use this as a piping bag, so the part that you cut off has to be very tiny.

Use the bag to squeeze a tiny drop on the back of the eyes and secure two of them to each round candy ball.

Using the same bag, pipe eight legs onto the peanut butter cookie, starting from the candy ball to the edge of the cookie.

Allow the chocolate to set before serving.