Cream 250 g butter and 200 g sugar with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour, baking powder and 1 pinch of salt and stir in. Halve the dough. Mix the jelly powder and 100 g buttermilk, add 1/4 teaspoon of food colouring to one half of the dough.
Pour the dough into a greased and flour-blown springform pan (26 cm Ø). Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 20-25 minutes.
Remove the cake from the oven, remove from the mould and let it cool on a cake rack. Clean the springform pan, grease and dust with flour. Mix 100 g buttermilk and cocoa and stir into the rest of the dough.
Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 20-25 minutes. Remove from the oven, remove from the tin and let cool on a cake rack. In the meantime form balloons of approx. 5 cm in size from fondant.
Place on wooden skewers and set aside.
For the buttercream, mix egg white and 300 g sugar in a bowl and hang over a hot, lightly boiling water bath. Heat the egg white-sugar mixture to 60 °C with a spoon, stirring constantly.
Remove from the heat and whisk with the whisk of the hand mixer for about 15 minutes until the beaten egg white has cooled down. Stir in 360 g butter bit by bit (may become slightly crumbly at first, just keep stirring).
Chill the cream for about 30 minutes.
Cut both bottoms in half horizontally. Place a cake ring around the lower dark base. Spread 1 tablespoon of fruit spread on top. Place the lower red cake base on top, spread 1/3 of the cream on top and chill for approx. 1 hour.
Also refrigerate the rest of the cream. 5. Place 2. red base on the cream layer, spread with 1 tbsp. fruit spread and cover with 2. dark base. Colour the rest of the cream pink with 1/4 tsp. food colouring and spread the cake with it.
Chill for about 1 hour.
Arrange the cake on a plate. Remove the sugar pearls from the chain bands and decorate the surface and edge of the cake with them. Put fondant balloons into the cake.