This delicious and impressive Frankenstein cake is an awesome addition to your Halloween party.
Cut parchment to fit in the bottom of two 8-inch round baking pans. Coat with nonstick cooking spray. Prepare cake mix according to package directions for two 8-inch cakes, replacing water with buttermilk and using vegetable oil and eggs. Pour evenly into pans and bake at 350 degrees for 34 to 38 minutes, until a toothpick inserted in the center comes out clean. Cool in pans on baking racks 15 minutes. Remove from pans, remove parchment and cool cake layers completely.
Meanwhile, prepare frosting. Using a stand mixer or hand mixer, combine butter, confectioners' sugar and milk. Beat on low until just combined, then on high 3 to 5 minutes, until fluffy. Mix green food coloring into frosting.
Heat heavy cream in a small pot until simmering. Place chopped chocolate in bowl of a stand mixer. Pour cream over chocolate and stir until smooth. Beat with whisk attachment on medium-high 5 to 7 minutes, until fluffy. Let ganache stand 10 minutes. Set aside ¼ cup, and transfer remaining ganache to a piping bag fitted with a flat tip.
Trim cake layers to make each flat. Place one layer on a stand. Spread ¾ cup of the green frosting evenly over top. Place second layer on top, then spread remaining frosting on sides of cake.
Pipe ganache in strips on top of cake to resemble strands of hair. Fill another piping bag, fitted with a small circular tip, with the remaining ganache. Pipe a mouth and stitches on face. Use a bit of ganache to secure Junior Mints on candy melts for eyeballs. Press eyeballs and gumdrop (for the nose) on the cake. Press Twix bars into the bottom sides of cake to resemble bolts.