First, for the filling, mix the pudding powder with about 4 tablespoons of milk and the sugar, bring the rest of the milk to a boil, stir in the mixed pudding powder, bring to a boil again until the mixture has thickened, then remove from the heat. Cut or break the chocolate into pieces and melt in the hot pudding while stirring. Transfer to a mixing bowl and let cool. Meanwhile, line the bottom of a 26-cavity springform pan with baking paper. Preheat the oven to 180°C top/bottom heat.
Beat the eggs with the water until creamy, then gradually add the sugar and continue beating until the mixture is thick and creamy. Add the flour, starch and grated orange zest and gently fold everything in. Pour into the prepared pan and bake in the preheated oven for about 25 minutes.
Once the chocolate pudding has become about room temperature, place in the refrigerator. Whip the cremefine with cream stiffener until stiff and fold in.
Chill again. Cut the cooled sponge cake twice crosswise, so that you have three layers that are as even as possible. Place the bottom one on a cake plate. Now bring the orange marmalade and Cointreau to the boil while stirring, and brush the bases with it.
Now spread about ¼ of the chocolate cream on the bottom layer, place the second layer on top, spread about 1/3 of the remaining cream on top. Place the top cake layer on top. Spread all around with the remaining cream and decorate with chocolate decorations or sweets as desired.