- Bake cake. Preheat oven to 350°F. Spray 6inch round baking pans with vegetable pan spray.
In medium bowl, combine flour, baking soda and salt. In large microwavable bowl, melt chocolate and butter for 2 minutes or until butter is melted. (Mixture can also be melted on top of stove in heavy saucepan over low heat.) Stir until smooth. Transfer to large bowl; add sugar and beat with electric mixer until well blended. Add eggs, one at a time, and vanilla; mix well. Add flour mixture alternately with milk; beat until well blended and smooth.
Pour into 3 prepared pans.
Bake 32-36 minutes or until toothpick inserted in center comes out clean. Cool in pan 15 minutes. Remove to cooling grid; cool completely before decorating.
Prepare buttercream. Prepare two batches of peppermint buttercream.
In a large bowl, beat shortening and butter with an electric mixer on medium speed 2-3 minutes or until well combined.
Gradually add sugar, one cup at a time, beating well between each addition, until frosting appears smooth. When all sugar has been mixed in, the frosting will appear dry.
Add milk, peppermint extract, salt, and vanilla. Beat at medium speed 3-4 minutes or until light and fluffy.
Ice Cake. Level, fill and stack cake layers with peppermint buttercream for a 6 in. high cake. Lightly crumb coat cake; chill until set, about 20 minutes.
Reserve remaining buttercream.
- Prepare parchment strips. Using ruler and pencil, make strips with parchment paper, 8 measuring 1½ in. wide and 8 measuring ¾ in. wide.
Decorate sides of cake. Ice cake smooth using reserved peppermint buttercream. Carefully apply the parchment strips to the cake, alternating the different sizes (1½ strip, ¾ in. strip, 1½ in. strip, etc.).
Once all the strips have been attached, carefully remove the 1½ in. strips.
Place cake on cookie pan to catch any falling pieces. Using your hand, lightly press the peppermint crunch candies onto all the open spaces.
Remove ¾ in. strips. Using Red icing pouch with round tip, pipe candy cane lines on all the open white sections.
- Decorate cookies. Melt 4 oz. Bright White candy according to package directions. Dip chocolate sandwich cookies ½ way into melted candy. Place on parchment paper-covered cake board. Sprinkle peppermint crunch candies on each dipped cookie. Repeat for a total of 6 cookies. Let chill until set, about 5 minutes.
Decorate top of cake. Prepare decorating bag with tip 1M and remaining peppermint buttercream. Pipe 6 swirls, evenly spaced, around top of cake.
Place cookies, with undipped cookie facing out, in between each swirl.
Sprinkle remaining peppermint crunch candies on top of swirls.