1Heat oven to 350°F. Grease bottoms only of 2 (8-inch) square cake pans with shortening or cooking spray.
2Make and bake cake mix as directed on box for 8-inch cakes. Cool 10 minutes. Run knife around side of pans to loosen cakes; remove from pans to cooling rack. Cool completely, about 1 hour.
3On serving plate, place 1 cake layer. Spread with about 1/2 cup white frosting. Top with second layer. Frost sides and top. Using black decorating icing, pipe desired designs on sides and top of cake. Place candles on cake. Store loosely covered at room temperature.