A classic Italian mimosa cake, often served in the spring for Womens day.
Preheat oven to 325F and grease and flour two 8 inch round baking pans.
To make sponge cake:
Beat eggs and sugar until creamy, firm and increased in volume.
Sift together flour and potato starch and carefully fold into egg mixture at little at a time, being carefully not to over whip it.
Pour into prepared cake pans.
Bake for 35-45 minutes, or until cake is slightly golden and you can poke a fork in the center and it comes out clean.
Remove from the oven and set aside to cool in pan.
Make cream layer:
Whip very cold heavy cream with confectioners sugar and set in fridge until later.
Slice vanilla bean open lengthwise, scrape out seeds into a bowl.
Use a lemon zester to get zest from 1 lemon, being careful to avoid the bitter white layer.
In a saucepan bring milk, lemon zest and vanilla seeds to a boil, and then immediately turn off the heat.
In a bowl, beat whole eggs and egg yolks with sugar.
Sift flour and stir into egg mixture until smooth.
Pour in the remaining milk mixture through a sieve into your egg mixture to remove lemon zest.
Return the mixture to the saucepan the heat over low heat for 5 - 10 minutes, stirring constantly when it comes to a boil for 2-3 minutes.
Remove from the heat and set aside to cool completely.
Once cooled, fold whipped cream mixture from fridge into milk mixture and set aside.
Prepare syrup to soak the sponge cake with: Bring water and sugar to a boil in a saucepan.
As soon as the sugar has dissolved, remove from the heat and stir in Kirsch liqueur.
Assembling the cake: With a serrated knife, cut each of the cakes horizontally in half.
Place one slice of sponge cake onto a rectangle baking pan.
Brush sponge cake with syrup.
Spoon one layer of cream sauce and cover with another slice of sponge cake.
Spoon another layer of syrup and cream sauce over sponge and cover with a 3rd layer of sponge cake.
Refrigerate for about 30 minutes
Slice the remaining sponge cake into 1/2 inch cubes.
Transfer cake to your serving plate.
Cover the outside with the remaining cream
Sprinkle sponge cake cubes over the top, covering the whole cake