Cut the vanilla pod lengthwise about 1 week before preparing the cake. Place in a container with candy, vodka and rhubarb nectar. Close it, shake vigorously once a day until the candy has dissolved.
For the buttercream, stir the pudding powder, 100 g sugar and 100 ml milk until smooth. Bring 400 ml milk to the boil, remove from the heat. Stir in the pudding powder, bring to the boil again while stirring and simmer for about 1 minute.
Place the pudding in a bowl, cover directly with foil and allow to cool at room temperature. Store 250 g butter also at room temperature.
Line the bottom of a springform pan (26 cm Ø) with baking paper. Separate the eggs. Beat the egg whites, if necessary in 2 portions with the whisk of the hand mixer until stiff, adding 150 g sugar and salt.
Stir in the egg yolks one by one. Mix flour and baking powder, sieve onto the egg cream and fold in carefully. Fill the mixture into the springform pan and smooth it down. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) bake for about 30 minutes. Remove from the oven and let it cool down on a cake rack.
Whisk the warm butter with the whisk of the hand mixer until creamy-white (approx. 15 minutes). Stir in the pudding by the spoonful. Stir cranberries until smooth, put aside approx. 2 tablespoons for decorating.
Remove the cooled cake from the tin, remove baking paper. Cut the cake twice horizontally. Place a cake ring around the lower cake base.
Sprinkle the bottom with approx. 3 tbsp. vodka-rhubarb liqueur. Spread the cranberries on top, leaving about 1 cm of edge free. Place the second base on top, sprinkle again with 3 tbsp. liqueur. Spread with about 1/4 of the butter cream.
Place the third base as a lid on top and sprinkle with another 3 tbsp. liqueur. Chill the cake for about 1 hour.
For the brittle, melt 1 tablespoon of butter in a frying pan. Slightly brown the almonds while turning them. Sprinkle with 4 tbsp. sugar and caramelise while stirring. Put the almonds on a piece of baking paper and spread thinly.
Let it cool down. Remove the cake from the ring.
Pour some cream into a piping bag with a perforated spout. Spread the remaining cream all around the cake. Crumble the brittle with your fingers. Sprinkle cake with brittle. Spray the rest of the cream as tuffs on the edge of the cake.
Decorate with cranberries set aside. Chill for about 2 hours. Use the rest of the liqueur for other purposes.