Assembling the princess birthday cake: 1. Bake three cakes in 8-inch round cake pans and one cake in a medium ovenproof glass bowl. Let cakes cool.
2. Cut off the dome off all of the 8-inch round cakes with a serrated knife. (Freezing the cake for about 45 minutes before you cut them will reduce the crumbs).
3. Cut a small hole in the middle of each layer; this is where the princes doll will go.
4. To keep your decorating surface clean while you frost, slide pieces of parchment paper underneath the bottom layer.
5. Using your offset spatula, place a dollop of frosting on one of the layers of cake, and spread it evenly. Place another layer on top, frost it, and place the last layer on top. Frost the top of the last 8-inch round cake and top with the cake baked in the overproof glass bowl (domed side up).
6. Make a crumb coat. This is a thin layer of frosting that seals in the crumbs and keeps the frosting clean and neat. Spread the frosting over the entire surface of the cake. To make the frosting smooth, take a strip of paper, cup it and place it at the bottom of the cake, sliding it evenly to the top of the cake.
7. Spread the frosting smooth around the hole in the top.
8. Freeze the cake for about 45 minutes to set the frosting.
Decorating the princess birthday cake: 1. Once the frosting is set, place a dollop of frosting on top and work your way down. Make the cake smooth using the paper technique, or add texture using your offset spatula. Try a fabric effect by making small swirls in the frosting.
2. Wrap the fashion dolls body with plastic wrap. If the doll has long hair you may consider wrapping that during the frosting process as well, to keep it clean.
3. Insert the princess doll into the hole, and add frosting to fill in any gaps.
4. Fill the pastry bag with pink frosting and pipe stars around the doll where it meets the cake. Cover her bodice with the frosting as well.
5. Add highlights to the dress with candy stars.
6. As a finishing touch, you can add a wand and hat made of paper and candy as well.
Some may say this is similar to a Bratz or Barbie birthday cake.