Preheat oven to 375 degrees F. Line a muffin pan with themed cupcake liners.

In a large bowl, sift together the flour, baking powder, baking soda, cocoa and salt. Set aside. In a large bowl, cream together the butter and sugar until light and fluffy, about 2 minutes. Add the eggs one at a time, beating well with each addition, then stir in the vanilla.

Add the flour mixture alternately with the milk; beat well. Fill the muffin cups 3/4 full. Bake for 15 to 18 minutes, until a toothpick inserted into the cake comes out clean.

Place softened butter into a bowl and beat in 2 cups of icing sugar. Add 2 Tablespoons heavy cream and vanilla. Add remaining icing sugar 1/2 cup at a time until you reach your desired consistency.

Spoon the frosting into a piping bag with no tip or a circular tip. Swirl the frosting onto the cooled cupcakes.

Melt the candy melts with the shortening for 25 seconds, stir, and reheat if necessary. Place a large marshmallow in the center of each cupcake and spoon 1-2 Tablespoons of the candy melts overtop. Use the back of a spoon to help the candy melts move if needed.

Repeat with the other ghost cupcakes. After each ghost has dried for about 5 minutes, attempt to attach the eyes - if the candy melts are still too soft, give it another couple minutes before re-attempting.