Buttercream Frosting

• Complete the center of your cake with a layer of frosting. Birthday cakes are often frosted and filled with buttercream frosting. Buttercream frosting is a combination of egg white, milk, granulated sugar, butter and vanilla extract. The milk must be heated and cooled first before adding the remaining ingredients. Then, you can frost your cake.
  
  

Pudding

• Make your cake like bakeries do, using pudding as the center filling. Select your preferred flavor. Use instant pudding mix and prepare according to directions, with one exception. Split the portion of milk required. Make it with half heavy cream and the remainder whole milk. Now, cover it with plastic wrap touching the top of the actual pudding. This prevents a surface skin from forming. When cool, the pudding will be very thick. You can now spread it as filling for the center of the cake.
  
  

Raspberry Filling

• Fill a cake with raspberry filling using fresh or frozen raspberries combined with sugar, lemon juice and cornstarch. The ingredients are then heated on a stove, causing it to thicken. After the mixture has cooled, spread it on the first layer of the cake. Set the top layer on the raspberry coated bottom layer and then frost the outside with the frosting of your choice.
  
  

Cream Cheese Filling

• Bake a carrot cake and complete it with cream cheese frosting. Cream cheese frosting is used for the outside of the cake and the inside layer. Ingredients for cream cheese frosting include powdered sugar, cream cheese, butter and lemon juice. Beat it until it is fluffy and spreadable. Coat the bottom layer, first. Position the second layer of cake on top. Frost the inside layer and top or do the sides, as well.
  
  

Cookie Crumble Filling

• Make your own ice cream cake as ice cream parlors do. Soften the ice cream by leaving it out at room temperature. Using a spring-form pan, cover the bottom with a thin layer of crumbled chocolate sandwich cookies. When the ice cream is spreadable, but not runny, spoon on a thick layer. Cover that layer with more crushed cookies and add a top layer of ice cream. Place the pan in the freezer. When the cake is hard-frozen, undo the hinge on the pan and slip the outer layer off. Now you can frost and decorate the outside.