Grease the springform pan (26 cm Ø) only at the bottom and dust with flour. Separate the eggs for the sponge cake. Beat the egg whites, 3 tbsp. cold water and 1 pinch of salt until stiff, while adding 75 g sugar and 1 packet of vanilla sugar.
Beat the egg yolks separately. Mix flour, starch, cocoa and baking powder, sieve on top and fold in. Brush into the form. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer) for approx. 20 minutes. Remove from the edge of the mould with a knife. Let the sponge cake cool down in the mould.
Wash orange hot, rub dry. Finely grate half of the peel. Squeeze the orange. Measure 80 ml orange juice and mix with the grated orange peel and liqueur in a small bowl. Dip the lady fingers briefly into the orange juice and let them steep for about 10 minutes.
Soak gelatine in cold water. Close a cake ring (about 8 cm high) around the cake base. Wash and clean the strawberries and put half (preferably small ones) aside. Dice the rest of the strawberries.
Whip the cream until stiff. Mix mascarpone, quark, 100 g sugar and 1 sachet vanilla sugar briefly. Squeeze the gelatine and dissolve at low heat. Stir in 2 tbsp. mascarpone cream and then stir into the rest of the cream.
First fold cream and then the strawberry cubes into the cream. Spread half the cream on the cake base. Spread the lady fingers on top. Possibly cut some lady fingers to size. Spread with the rest of the cream.
Place whole strawberries close together on the cream and press them in gently. Chill the cake for about 4 hours.
Remove the cake from the cake ring. Warm up the fruit spread just before serving. Drizzle the strawberries with it.