Once your layers are cooled, frost and fill with Almond Buttercream and smother top with Semisweet Chocolate Ganache, allowing it to drip down the sides of the cake. Gently arrange several of your ghosties on top of the ganache while still soft and drippy.
Almond Buttercream [click to print]
3 c. powdered sugar
1/4 c. butter, softened
1/4 tsp. salt
1/4 tsp. almond extract
2-3 T. whole milk
Combine sugar, butter, salt and extract in mixing bowl. Turn mixer on low speed and gradually add milk, one tablespoon at a time, until frosting reaches desired consistency. For this cake, you want the frosting to be stiff enough that when you lift the beaters, stiff peaks form. If it droops back into the bowl, it will be too soft to hold its shape on the cake. To fix that, just add a little more powdered sugar until it stiffens.
Chocolate Ganache [click to print]
3/4 c. chocolate chips (milk or semi-sweet)
2/3 c. heavy whipping cream
Measure chocolate chips in small mixing bowl; it should hold about 4-6 cups to allow for stirring room. Heat cream in saucepan until it begins to get frothy. Immediately remove from heat and pour over chocolate chips. Allow mixture to sit for two minutes then stir until well combined and smooth. Allow ganache to cool about 15 minutes or until it is the consistency of thick molasses and mounds slightly when dropped from a spoon.
Source: Adapted from Betty Crocker Ultimate Cake Mix Cookbook