Layer Cake with Blueberry and Mascarpone Cream
Measure out all needed ingredients accurately. Grease the bottom of a springform pan.
Beat the yolks with half the sugar and with the vanilla sugar until fluffy. Beat the egg whites into a meringue until medium stiff, then sprinkle in the remaining sugar and continue beating until stiff. Fold meringue into egg yolk mixture.
Sift the flour with the cornstarch through a sieve into the egg mixture and fold to combine.
Pour the batter into the greased springform pan, smooth the surface and bake on the middle rack of a preheated oven at 175°C (approximately 350°F) for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Remove from the oven, let cool slightly, then carefully loosen edge of cake with a thin knife from side of springform pan. Place cake on a wire rack and let cool for at least 2 hours.
For the mascarpone cream: Warm the whipping cream with the chopped white chocolate in a saucepan, continuously stirring, until melted. Let cool slightly. Add spoonfuls of the mascarpone to the chocolate mixture, beating well with a mixer.
Soak half of gelatin in a bowl of cold water and other half in a separate bowl of cold water. Strain blueberries in a sieve, colleting the juice in a bowl. Purée the berries. In a saucepan, dissolve half of gelatin in some of the berry purée over low heat while stirring. Warm the blueberry juice slightly, add remaining gelatin and dissolve, continuously stirring, then add to the mascarpone mixture and mix well.
Cut the cake once, so 2 layers are formed. Enclose the bottom half with a cake ring, cover with the blueberry puree and then top with about 1/3 of the mascarpone cream. Place the second layer on top and spread with about 150 ml (approximately 1/2 cup) of the mascarpone cream. Chill the cake and the remaining mascarpone cream in the refrigerator until the cream begins to thicken and is spreadable. Remove cake ring and cover cake with the remaining mascarpone cream.