Method

1. Preheat the oven to 170C/325F/Gas 3. Grease and line the 23cm/9in cake tin and 15cm/6in cake tin.

2. Cream the butter and sugar together in a bowl until light and fluffy, then beat in the eggs, one at a time, until well combined.

3. Fold in the flour and cocoa powder, then stir in the melted chocolate until well combined.

4. Divide the mixture among the prepared cake tins.

5. Bake the 23cm/9in cake for 1 hour-1 hour 15minutes and the 15cm/6in cake for 45 minutes or until the cakes are golden-brown and a skewer inserted into the centre of the cakes comes out clean.

6. Remove the cakes from the oven and set aside to cool, then carefully remove them from the tins and allow to cool completely.

7. Meanwhile for the white chocolate buttercream, cream the butter, vanilla and icing sugar together in a bowl until light and fluffy. Stir in the melted chocolate.

8. For the dark chocolate buttercream, repeat the method for the white chocolate buttercream.

9. For the ganache, heat the double cream in a saucepan until just boiling, then remove from the heat. Pour the cream over the chopped chocolate and stir until the chocolate has melted and the mixture is smooth. Set aside to cool slightly, or until the mixture has thickened.

10. Carefully cut each cake in half horizontally and fill with the dark chocolate buttercream. Spread a teaspoon of buttercream onto each cake board and place the cakes onto them.

11. Spread the white chocolate buttercream over the top and sides of each cake until covered. Chill in the fridge for 30 minutes, or until the icing has set.

12. Spread the ganache over each cake with a palette knife, trying to make it as smooth as possible. Chill in the fridge for 30 minutes, or until the icing has set.

13. To stack the cakes, hold a dowelling rod at the side of the 23cm/9in cake and mark with a pencil where the icing comes to. Cut the rod and three others to the same length. Push the rods into the cake about 5cm/2in away from the sides, to form the four corners of a square in the centre of the cake. Place the pillars on top of the largest cake, positioning each one over a dowelling rod, then top with the 15cm/6in cake. Decorate with fresh flowers.