Makes 12 servings
1 Combine the vanilla frosting with the peanut butter, mixing well until smooth. Spoon the frosting into a freezer-weight ziplock bag. Spoon ¼ cup of the chocolate frosting into a freezer-weight ziplock bag. Press out the excess air and seal the bags.
2 Line a cookie sheet with wax paper. As you make the parts, transfer them to the cookie sheet. For the legs and ears, cut 5 of the peanut butter cookies in half crosswise with a serrated knife (see photo, above). For the feet, remove ¼ inch from one edge of 2 of the peanut butter cups. For the muzzle, cut ½ inch from 2 sides of the remaining peanut butter cup on an angle to create a point. For the nose, cut the chocolate kiss in half lengthwise and discard one piece.
3 Remove the chilled cake assembly from the freezer. For the ears, attach 2 of the cookie halves, cut side down, on top of the head cake, about 2 inches apart, with some milk chocolate frosting. For the muzzle, attach the pointed peanut butter cup to the head cake with some frosting, rounded side down, with the point just below the center. For each leg, attach a cookie half, cut side down, against the base of the body using a dot of frosting. Attach 3 more cut cookies to each leg, and finish with a trimmed peanut butter cup, cut side down. Return the cake to the freezer.
4 For the bow, unroll the fruit leather and fold it in half crosswise to make a double thickness. Press firmly to adhere. Cut the strip into two 5-inch lengths and two 3-inch lengths. Loop each of the longer pieces in half and pinch the ends together (see photo). Overlap the pinched ends of each loop and press them together. To make the tails of the bow, cut a V-shaped notch from one short side of each of the 2 smaller pieces; reserve one of the cut-out notches. Pinch the straight end of each tail piece and press together with the pinched ends of the loops to make the bow. Attach the reserved notch in the center with a dot of water to cover the pinched area. Place the bow assembly on the cookie sheet.
5 Remove the chilled cake from the freezer. Spread some of the milk chocolate frosting on the cookie legs and smooth, leaving the flat side of the peanut butter cup unfrosted. Starting at the edge of the peanut butter cup, use a fork to pull the frosting in a downward and outward motion (see Forked Frosting), working in overlapping rows to the top of each leg. Spread some of the milk chocolate frosting on the body and smooth. Starting at the base of the body cake, continue forking the frosting in one direction, in overlapping rows, to the neck. Spread the remaining milk chocolate frosting over the head and backs of ears, leaving the peanut butter cup muzzle unfrosted, and smooth. Starting at the neck, continue forking the frosting in one direction, in overlapping rows, up to and including the ears.
6 Starting at the platter, between the legs, press the licorice lace, vertically, in the center of the body. Snip a ¼-inch corner from the bag with the peanut butter frosting. For the chest fur, start with a narrow row in the center of the body and pipe overlapping rows of peanut butter frosting, always pulling down and out, making the rows wider as you work up to the neck to create a V-shape. Starting at the top of the cookie ears, pipe rows of the peanut butter frosting to cover the front of the ears. Pipe some peanut butter frosting over the muzzle and smooth. Let the muzzle frosting dry to the touch for about 25 minutes, then add texture to the muzzle by lightly pressing a paper towel into the frosting (see Toweled Frosting).
7 Snip a ¼-inch corner from the bag with the milk chocolate frosting. For the arms, remove and discard the filling from the remaining peanut butter cookie. Pipe milk chocolate frosting on one side of each cookie. Using a dot of frosting, attach a cookie, frosted side out, to each side of the body cake, close to the head. Starting at the bottom of the arms, use a fork to pull the frosting in a downward and outward motion, working in overlapping rows to the top of each arm. Pipe spikes of milk chocolate frosting to cover any flaws on the cake.
8 Attach the cut chocolate kiss to the muzzle, pointed end down, for the nose, using a dot of frosting to secure. Place the black candies above the muzzle for the eyes. Attach the bow to the side of the neck with a dot of frosting. Add the candy cane, if using.