Prepare Icing We suggest that you tint all icings at one time while cake cools. Refrigerate tinted icings in covered containers until ready to use.
Make 4 1/2 cups buttercream icing: Tint 2 1/4 cups dark brown (add a little red to brown) (thin 1 1/4 cups with 1 tablespoon and 1/4 teaspoon light corn syrup)
Tint 3/4 cup brown (add yellow color to brown)
Tint 1/2 cup black
Reserve 1 cup white (thin 1/2 cup with 1/2 teaspoon light corn syrup)
Decorate in Order
Use thinned dark brown icing and spatula to ice sides of guitar and fingerboard smooth.
Use thinned white icing and spatula to ice sides around fingerboard and headstock smooth.
Use black icing and spatula to ice headstock and sound hole smooth.
Use tip 3 and black icing to encircle sound holes.
Use tip 3 and black icing to pipe dot tuners.
Use tip 16 and black icing to cover bridge with stars.
Use tip 16 and brown icing to cover guitar body with stars.
Use tip 3 and white icing to pipe horizontal frets and then pipe vertical strings.
Use tip 3 and white icing to pipe dots to cover ends of strings.
Use tip 21 and white icing to pipe shell bottom border around fingerboard.
Use tip 21 and dark brown icing to pipe shell bottom border around guitar body.
Baking Instructions Preheat oven to 350°F or temperature per recipe directions. Your cake will unmold easily, without sticking, when you prepare the pan properly. Grease the inside of pan using a pastry brush and solid vegetable shortening (do not use butter, margarine or liquid vegetable oil). Spread the shortening so that all indentations are covered. Sprinkle about 2 tablespoons flour inside pan and shake so that flour covers all greased surfaces.
Turn pan upside down and tap lightly to remove excess flour. If any shiny spots remain, touch up with more shortening and flour to prevent cake from sticking. (You can use vegetable oil pan spray or vegetable oil pan spray with flour, in place of solid shortening and flour, or use Wilton Cake Release, for perfect, crumb-free cakes or Bake Easy Non-Stick Spray for easy release).
Make one 2-layer cake mix according to package or recipe directions. Pour the cake batter into pan, and if necessary, spread the batter around with a spatula to fill all areas of the pan evenly. Be careful not to touch sides or bottom of pan.
Bake cake on middle rack of 350°F oven for 30-40 minutes or until cake tests done according to recipe directions.
Remove cake from oven and cool on cake rack for 10 minutes. While the cake is still in the pan, carefully slice off the raised center portion of the cake. This allows the cake to sit more level and helps prevent cracking.
To remove cake from pan, place cooling rack against cake and turn both cake rack and pan over. Lift pan off carefully. Cool cake at least one hour. Brush loose crumbs off cake. To transfer cake to serving board, hold a cake board against cake and turn both cake and rack over. Lift off rack. Hold another board against bottom of cake and turn cake over. Be sure to hold cake, rack and board close together while turning to prevent cake from cracking.