For the chocolate-vanilla zebra cake, first preheat the oven to 180 °C top and bottom heat. Butter the cake pan and sprinkle with flour, tapping out any excess flour.
Separate the eggs. Beat the egg yolks with 200 g sugar, vanilla sugar and salt until creamy. Add the oil and 125 ml lukewarm water and stir in. Mix flour and baking powder and stir into the egg yolk-sugar mixture.
Beat the egg whites until stiff, adding the remaining sugar. Gently fold in the beaten egg whites and divide the mixture in half. Stir the cocoa powder into the first half. Flavor the second half with the vanilla extract.
Pour a little light mixture into the mold, then add a little dark mixture on top (the thinner the layers, the stronger the zebra pattern will be. Repeat this process until both masses are used up.
Bake the cake in the oven for 50 to 60 minutes (test with a stick!), take it out and let it cool on a cooling rack.
Meanwhile, for the ganache, chop the chocolate into small pieces. Heat the whipping cream in a saucepan and melt the chocolate in it. Add the liqueur and whisk until smooth.
Drizzle the chocolate-vanilla zebra cake with a little Amarula ganache, cut into pieces and serve. Serve the remaining ganache separately.