Hands-on time 17hr, plus cooling and chilling. Cooking
time about 274hr. Serves 18-20
For the white chocolate cake:
- 250g (9oz) unsalted butter, softened, plus extra to grease
. 125g (40z) white chocolate, chopped
. 175g (6 oz) caster sugar
2tsp vanilla extract
- 5 medium eggs, beaten
- 225g (8oz) self-raising flour
For the dark chocolate cake:
- 250g (90z) unsalted butter, softened
100g (37202) dark chocolate (70% cocoa solids),
chopped
. 175g (6 oz) self-raising flour
50g (2oz) cocoa powder
- 225g (80z) caster sugar
- 5 medium eggs, beaten.
For the ganache:
• 200g (7oz) dark chocolate (70% cocoa solids), finely
chopped
3tbsp golden syrup
150ml (14pint) double cream
For the white chocolate buttercream:
125g (4oz) white chocolate, chopped
• 175g (6 oz) unsalted butter, softened
• 250g (90z) icing sugar
For the glaze:
• 125g (4oz) dark chocolate (70% cocoa solids), finely
chopped
• 75g (30z) unsalted butter, softened
To decorate
. 8 Marbled Viennese Whirls (optional)
1. Make the white chocolate cake: preheat oven to 180°C (160°C fan) mark 4. Grease and line a 20.5cm (8in) round cake tin, at least 7.5cm (3in) deep, with baking parchment.
2. Melt white chocolate in a heatproof bowl set over a pan of simmering water - being careful not to overheat. Set aside to cool for 10min.
3. In a large bowl (or freestanding mixer) beat butter and sugar until pale and fluffy – about 5min. Gradually beat in vanilla, followed by the eggs, mixing in a spoonful of flour if it looks like it might curdle. Fold in flour and melted chocolate. Scrape into prepared tin and bake for 1hr or until a skewer inserted into the centre comes out clean.
Cool in tin for 5min, then transfer to a wire rack to cool completely
4. Make the dark chocolate cake: grease and line the clean cake tin with baking parchment. Melt dark chocolate as before; set aside to cool for 10min. Sift flour and cocoa powder into a bowl; set aside.
5. Combine the dark chocolate cake ingredients as in step 3, omitting the vanilla, and substituting the dark chocolate and cocoa/flour mixtures. Scrape into prepared tin and bake for 55min or until a skewer inserted into the centre comes out clean. Cool in tin for 5min, then transfer to a wire rack to cool completely.
6. Make ganache: put chocolate, golden syrup and cream in a heatproof bowl set over a pan of barely simmering water. Heat, stirring, until melted and smooth. Take off heat; cool completely.
7. Level both cakes, if needed, making sure they are the same height. Next, slice each cake in half horizontally to make 4 layers.
8. Use a round 6.5cm (2%2in) biscuit cutter (or make yourself a paper template) to cut out a disc of cake from the centre of each layer.
Carefully remove discs on to a tray or board. Next, use a sharp knife to cut each cake ring into 2 thinner rings of the same width. You should have 4 large cake rings, 4 medium cake rings and 4 small cake discs (don't worry if any break, you can stick them back together later).
9. On to a board, lay a large white chocolate cake ring.
Spread ganache on the inside vertical edge of the ring and position a medium chocolate ring inside it. Spread the inside vertical edge of the chocolate ring with ganache, then slot in a small disc of white chocolate. Thinly spread ganache over the top of this layer.
Lay a large dark chocolate ring on top of the first layer and continue to build a second layer, alternating colours.
Repeat to build a third and fourth layer on top of the first two, alternating colours.
10. Make the buttercream: Melt white chocolate as before.
Set aside to cool for 15min. Put the softened butter into a separate large bowl and sift over the icing sugar. Starting slowly, beat together using a handheld electric whisk (or a freestanding mixer) until fluffy and combined. Beat in cooled white chocolate.
11. Using some of the buttercream, thinly spread a smooth layer over top and sides of cake to act as a crumb coat. Chill for 30min.
12. Transfer cake to a plate or stand and spread over remaining buttercream. Chill for 30min.
13. Make the glaze: Put chocolate and butter in a medium bowl set over a pan of barely simmering water; stir until melted. Cool for 5min. Pour over the iced cake, smoothing with a clean palette knife and encouraging it to drizzle down the sides. If you like, decorate with Marbled Viennese Whirls and serve.