Preheat the oven to 350 degrees F. Spray each cake pan and 1 of the cups from the muffin pan with nonstick cooking spray. Coat the pans lightly with flour, tapping out the excess.

In the bowl of a standing mixer, combine the cake mix with butter. Add the eggs, one at a time, and mix to incorporate. Slowly add the buttermilk and mix on medium for 2 minutes, until well incorporated. Fill each prepared pan and muffin cup 2/3 of the way to the top. Bake for 30 to 50 minutes or until tops are golden brown and a toothpick inserted in the center of the cake comes out clean. The large cake will take closer to 50 minutes, while muffin will be closer to 15 minutes. When cool enough to handle, remove the cakes from the pans and cool completely, right side up, on a wire cooling rack.

Royal icing: In a medium bowl beat together the confectioners' sugar, meringue powder and lemon juice with a hand mixer or whisk, and slowly add some of the water until smooth. Continue to add water by the teaspoonful with the beaters running until the icing drops from the beaters, but holds a line when drawn in with the back of a spoon. Fill the resealable bag with royal icing and snip the corner when ready to use.

To assemble: Using a clean pastry brush, lightly coat the sugar cones with piping gel. Hold the cones over a plate and sprinkle each with the pink and orange sprinkles. Make sure the cones are completely coated with nonpareils. Set aside to dry slightly.

Using a serrated knife, level the tops of each of the square cakes and the muffin. Adhere 1 square cake to the 7-inch square cardboard cake board, and the muffin cake to the 3-inch round cardboard cake board with a dab of frosting. Put a layer of frosting on top of the square cake and put the second layer on top of that. Ice both cakes with a thin layer of frosting and put in the refrigerator to set up about 15 minutes. Ice the cakes again with a slightly thicker layer of frosting.

Knead the fondant to make it more pliable. On a clean surface dusted with cornstarch roll out 3/4 of the fondant to 1/4-inch thickness. Lift with the backsides of your hands and put it over the center of the frosted square cake. Lightly dust your hands with cornstarch, and smooth the fondant down and around sides of cake. Lift the cake up and trim the excess fondant close to the cake board with kitchen shears or a paring knife. Repeat with the small muffin cake and the remaining fondant, then place center it on top of the square cake.

Pipe a small bead of royal icing around the base of each sugar cone and put 1 on each corner of the square cake and 1 atop the center of the small round muffin cake. Using royal icing for 'glue' adhere the licorice candies vertically around the sides of the small round cake, close to the top of the cake, spacing them out. Take 2 pink and 1 orange licorice twists and twist them together to form 1 rainbow twist. Repeat with the remaining twists. Secure the licorice twists vertically to the 4 corner edges of the cake with royal icing and toothpicks, if needed. It should cover the edge from the bottom of the cake to the top. Cut 2 orange sour candies in 1/2 along the diagonal and put each 1/2 atop the licorice twists. Arrange 5 orange (Spree) candies in a horizontal line towards the top of 1side of the cake. This will be the front of the cake. Attach the strawberry and cherry candies in a grid pattern close to the bottom of the cake, under the line of orange candies to form a doorway. Cut the remaining orange sour candies in 1/2 on the diagonal, and glue each 1/2 on top of the doorway, pointed side up. Glue the gum vertically along the top edges of the square cake and on the top edge of the round muffin cake making sure to leave a 1/2-inch space between each. Glue the orange segment candies, flat edge down, all along the bottom edge of the square cake, but not over the door. Let the icing sit for 1 hour to dry before transferring the centerpiece to a cake pedestal.