This is an example of a typical birthday cake in Italy. In the US, batters with fats and baking powder and fat-based cream are more common. In Italy we prefer this kind instead, layer cakes based on pan di spagna and crema pasticcera (or other similar egg based creams, such as chocolate pastry cream or zabaione).
US cakes tend to have foamy decorations made with various icings. They look nice but they do not taste good. Egg based creams taste much better, but you cannot decorate as you would do with US icings. If you really want some decoration, try using two creams of different colors (eg plain pastry cream and chocolate pastry cream), or add dark chocolate shavings. Marzipan works well too, and decent quality marzipan is available in many stores.
An assembled birthday cake will last up to 1 week in the refrigerator, but it is best eaten within two or three days. However, the taste is definitely better if you leave it for a few hours in the refrigerator before eating it.
Refer to the other recipes in this web page for the various components of the cake. This recipe will make a 9 inch cake, enough for 8-10 people.
Preparation If you want to use liquor syrups, prepare them in advance. In a small pan over medium, bring the water and the sugar to boil, mixing from time to time, until the sugar is completely dissolved. Let cool, then add the liquor.
Cut the pan di spagna in half horizontally. Accomodate the bottom on a large dish, possibly on a cardboard base (that will make it easier to cut). Pour 1/2 of the juice or of the syrup on the bottom. Pour a little less than half of the cream on the base (be careful not to spill it ouside the cake). I would also add some sliced ripe fruit here (strawberries, but also other berries, bananas, apricots, kiwi)
Cover with the top half of the pan di spagna. Again, pour fruit juice or liquor on the pan di spagna. Cover the top and the sides of the cake with the remaining cream (you may not need to use it all). Level and make the surface smooth with the back of a big knife or any other flat utensil.
It would be better to divide the pandispagna in three or four layers, rather than two, putting cream between each layer. However, it is rather difficult to cut a pan di spagna in thin layers, and you may not want to attempt it the first time that you prepare a cake. To cut a pan di spagna in thin layers, use a long serrated bread knife. Slowly cut a small circular trace on the outside of the cake, to guide the subsequent cutting. Once the whole trace is done, start cutting very slowly exactly along the trace. Do not cut all the way through the cake. Rather, cut a little, then rotate the cake and cut around. The process is easier than it sounds, but one has to go really slowly. The pan di spagna should be cut when completely cooled. Even better if it is frozen (which I always do).
Cut the fruit in pieces, the strawberries in half, the kiwis and bananas in horizontal slices. For appearance, dip the sliced fruit in a mixture of lemon juice and water, so that they do not oxidize and remain fresh looking. Accomodate the sliced fruit on the top of the cake, to form colorful patterns of red and green. (I use strawberries for red, kiwi for green and bananas for white - red white and green being obviously the colors of a certain flag...) You may add some whipped cream on top, if you like. Refrigerate the cake and serve cold.