For the Holundertörtchen, line half of a household baking tray (30 x 40 cm base) with baking paper. Preheat oven to 190 °C (top and bottom heat). Sift together flour and cornstarch. Beat eggs, powdered sugar, salt, vanilla sugar and grated lemon peel until well frothy (at least 10 minutes). Slowly pour in Kronenöl Spezial with fine butter flavor while stirring constantly, fold in flour mixture.Spread the mixture smoothly onto the baking paper and bake for about 15 minutes on the bottom rack. Remove from oven and let cool. Use a cake cutter to cut out 6 cake layers and place each of them as a layer in the cake cutter.For the cream, whip the whipped cream and chill. Soak the gelatine in cold water. Mix elderberry syrup, yogurt and powdered sugar until smooth. Squeeze gelatin well and dissolve warmly with 50 ml elderberry mixture. Mix with the elderberry base and fold in whipped cream. Pour the cream on the dough base and smooth it. Chill for 4 hours. Remove the elderberry cakes from the molds and top with chocolate rolls and elderflowers.