• Bake the sponges one day ahead of serving. Prepare the buttercream filling and assemble and decorate the cake on the day of serving.

To Make The Cake

• Preheat the oven to 160c/ gas mark 3.
• Prepare the sandwich tins by greasing and lining them with greaseproof paper.
• Place the white chocolate, milk, light brown sugar and 85g of the caster sugar in a deep saucepan and bring to the boil, stirring with a spatula.
• Place the butter and the remaining caster sugar in a mixing bowl and cream together until pale and fluffy.
• Beat the eggs lightly in another bowl and slowly add the butter mixture while whisking quickly.
• Sift the flour, baking powder and salt together and add to the butter mixture in two batches. Mix together at a slow speed until the batter is just combined.
• Slowly pour the hot chocolate mix into the batter in a thin and steady stream,  mixing at a medium speed. Scrap the bottom of the mixing bowl with a rubber spatula to make sure the batter is well combined.
• Immediately pour the sponge mix into the lined cake tins, dividing the batter evenly. If you find it difficult to measure by eye, use your kitchen scales to weigh out the amount of cake mixture for each tin.
• Bake for 25-30 minutes, depending on your oven. If you are using deeper cake tins, the sponges will take longer to cook. The sponges are cooked when the sides are beginning to shrink away from the edges of the tins and the tops are golden brown and spring back to the touch. If in doubt, insert a clean knife or wooden skewer into the centre of each sponge, it should come out clean.
• Once the sponges are baked, let them rest for about 30 minutes outside of the oven. Once just warm, run a knife all the way round the sides of the tin, remove the cake from the tin and leave to cool completely on a wire cooling rack.
• Once cool, wrap the sponges in cling film and then rest it overnight at room temperature. This will ensure that all the moisture is sealed in and the sponges firm up to the perfect texture for trimming and layering. When trimmed too soon after baking, the sponges tend to crumble and may even break into pieces.

To Make The White Chocolate Buttercream

• Place the cream in a saucepan and bring to a bare simmer. Place the white chocolate in a bowl and pour the hot cream over the top. Whisk together until smooth. Once combined, leave to set at room temperature; the white chocolate ganache should have the consistency of very soft butter.
• Place the butter and icing sugar in a mixing bowl and cream together until pale and fluffy.  One spoonful at a time, add the white chocolate ganache to the mixture and stir through until combined.

To Assemble The Cake

• Trim and sandwich together the three sponge layers using the passionfruit jam. Reserve one tablespoon of the chocolate buttercream for the piped decoration, then with the remaining buttercream, cover or mask the top and sides of the cake. (More detailed instructions how to do this are in the book) Chill until set.

To Decorate

• Place the cake either on a cakestand or on top of the turntable covered with a piece of greaseproof paper.
• Place a round nozzle into a plastic piping bag and fill with the remaining buttercream. Divide the top of the cake into 12 equal segments. At the top edge pipe a series of double swags (I managed a less elegant single swag!!) all round the sides, revolving the turntable as necessary.
• To finish, pipe dots on top of the swag joints and pipe a row of dots all around the bottom edge of the cake. (More detailed instructions on this are elsewhere in the book). If the cake has been placed on greaseproof paper, chill until the piped dots are set before transferring to a cakestand.