Separate eggs. Beat the egg whites until stiff, adding 125 g sugar and 1 packet of vanillin sugar. Stir in the egg yolks one after the other. Mix flour, almonds and baking powder and fold into the egg mixture.
Line a springform pan (26 cm Ø) at the bottom with baking paper, put the dough into it and smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 25-30 minutes. Soak the gelatine in cold water.
Mix champagne, lime juice and 25 g sugar. Squeeze the gelatine and dissolve in a small pot at low heat. Add the champagne-juice mixture while stirring and let it gel in the refrigerator. Whip 3 cups of cream until stiff, pouring in the remaining sugar and vanillin sugar.
When the champagne mixture begins to gel, fold in the cream and lime zest. Cut the sponge twice horizontally. Place a cake ring around the lower cake base and spread half of the cream mixture on top.
Place the second base on top and spread with the remaining cream. Place the third base as a lid on top and leave to set in the fridge for about 2 hours. Whip the rest of the cream until stiff. Remove the cake ring and spread the cake with the cream.
Crumble the meringue and sprinkle it all around the cake. Decorate as desired with slices of lime and a spiral. Makes about 12 pieces.