Prepare your Double Chocolate Cookie Bars. Allow to cool and set aside.
Prepare your buttercream per the instructions of the recipe. Make sure to make without color/cocoa, remove ⅛ of the non colored icing before proceeding with coloring icing black or adding cocoa to deepen color.
Place all the white buttercream frosting in a tipless piping bag, and place about 1 cup of black buttercream frosting in a tipless piping bag. Set aside.
Place a piece of parchment on a baking sheet, and have another ready close by. along with a measuring cup or flat bottomed cup.
Use the scissors to cut the piping tip of the bag with white frosting - you will only need to cut about ¼" to ½".
Hold in place about ½" above the parchment paper. Squeeze the piping bag from the top with your dominate hand while using a fingertip to gently keep the bottom in place. Squeeze gently until you have a dollop of frosting on the parchment paper about 1" wide and ½" tall. Repeat.
When finished place the 2nd sheet of parchment gently over the dollops but to not press down. Use the measuring cup to gently and evenly flatten the dollops of icing. Do not smash down all the way, you are only looking to lighten flatten the dollop.
Place the baking sheet with the white dollops in the refrigerator while we move on to the next step.
We now move on to frosting the cookie bars. Place the remaining black buttercream onto the cookie bar and use your offset spatula to help spread it evenly across.
Clean the offset spatula, and remove the white dollops from the refrigerator. Make sure you have allowed at least 20 to 30 minutes to pass so they are firm.
Remove the top piece of parchment carefully, and then use your offset spatula to gently slide under the first dollop. Be gentle to not break it. It should slide under easily if cold enough. If it breaks easily then place back into the refrigerator for another 15 minutes and try again.
After you have successfully lifted the white dollop than place on top of the cookie bar. Repeat and add them as little or as many as you'd like to the cookie bar.
Once you have placed all your white dollops scattered on the cookie bar it is time to begin decorating them with Jack's face! Take your black buttercream in the piping bag and cut a small hole at the tip - about ⅛" or smaller. You are going for small details so you need a small opening. You can also opt to use a Wiltons tip #1 or #2.
You will hold the piping bag with your dominant hand, and use your other hand to help guide the bag. Gently squeeze and begin with placement of the eyes, followed by the mouth finishing with the nostrils. Repeat until all white dollops are decorated.
Optional! If you'd like to add detail to the parts of the cookie bar not covered with Jack then you can! I opted to add swirls, lines and stitches randomly.