1 For the cake: heat the oven to 180°C (160° fan) 350°F gas 4. Grease 2 x 20cm|8" cake tins and line the bases with non-stick baking paper.
2 Whisk together the eggs and sugar until thick and fluffy.
3 Sift together the flour and cocoa 3 times and gently fold into the cake mixture.
4 Spread 1/5 of the mixture into each tin and bake for about 7 minutes until just firm. Repeat with the remaining mixture, using just 1 tin for the last 1/5 of the mixture. Cool in the tins for a few minutes, then place on a wire rack to cool completely.
5 For the syrup: heat the sugar and water in a pan until the sugar has dissolved. bring to a boil, remove from the heat and set aside to cool. Stir in the liqueur.
6 Brush each cake layer with syrup.
7 For the filling: combine the white chocolate and cream, stirring until smooth. Cover and chill until spreadable.
8 Spread the cake layers together with the chocolate cream.
9 For the topping: stir together the chocolate and butter. Set aside until thickened, but pourable.
10 Pour the topping over the cake, allowing it to run down the sides. Decorate with sugar flowers.