I've finally gotten around to writing down the recipe for this cake! Now all of you can have a taste, because it's DELICIOUS. I dreamt up this white chocolate chip cake with caramel filling, white chocolate Swiss buttercream and white chocolate ganache for a friend's baby shower. It took me two days to make and by the time I had finished there was blue buttercream on everything, including both dogs and the light switch. This recipe isn't for the faint hearted or the impatient. There are a lot of steps and a lot of ingredients and I would suggest buying extra sugar and eggs in case you miss a step and end up messing something up (I screwed up the caramel sauce because it was 1am and there was blue buttercream on my notes). But it's worth it, this cake is a show stopper.
Preheat the oven to 180 °C. Grease and line four 18cm springform pans.
Cream the butter and sugar together until light and fluffy, then add the eggs one at a time, while still beating with an electric mixer, followed by a tablespoon of flour between each egg. Beat until very light and fluffy. Add the vanilla seeds.
Combine the flour and baking powder. Mix the milk and water. Turn your mixer down to the lowest setting. Add a tablespoon of dry ingredients followed by a tablespoon of the milk mixture to the creamed butter mixture until all combined. Gently fold in the white chocolate chips. Divide the batter in two and colour half the batter blue.
Spoon batter into the line springform pans and bake for 35 minutes, or until a skewer comes out clean.
Remove from oven and allow to cool completely, this takes at least 4 hours in the fridge.
In a small pot, gently heat the cream and butter until the butter has melted. Remove from heat and add the vanilla.
In a larger pot, combine the sugar, corn syrup, and water. Heat over a medium high flame. Do not stir, it will cause the sugar to crystallise.
Continue to boil the sugar mixture until the bubbles begin to get smaller and it becomes amber-colored.
Remove from heat, and pour in the warm cream mixture, whisking constantly to avoid lumps or crystals.
Immediately transfer the hot mixture to a heat-safe vessel and cool completely.
The Swiss Buttercream
Place the egg whites and sugar in a mixing bowl. Set over a pot of simmering water, and whisk continuously, until the mixture is hot, opaque, and the sugar is completely dissolved (should not feel gritty between your fingers), about 5 minutes.
Whip the mixture on high speed, until stiff peaks form and it has completely cooled.
Add the butter, a tablespoon at a time, whipping well after each addition. If it begins to look curdled, continue to beat until it comes back together, before adding the remaining butter.
Mix in the vanilla, food colouring and melted white chocolate until well blended.
White chocolate ganache
Make the ganache just before you start assembling and decorating your cake.
Combine the white chocolate and cream in a dry and heatproof bowl over simmering water. (Do not let the water touch the bowl).
Stir occasionally until both chocolate and cream are well combined.
Allow to cool to room temperature.
Assembling the cake
I found it best to assemble the cake over two days. Craftsy has an excellent, free mini-class on assembling and applying the buttercream to a layered cake. You do have to register to view the videos, but it's worth it. You can find it here.
I divided each of the four cakes in half. Then assembled as follows: Layer of cake, brush on simple syrup, layer of buttercream, layer of caramel, repeat. Once you've assembled all the layers coat the outside of the cake in your crumb layer of buttercream, then allow to set in the fridge over night. The following day, make your ganache, coat your cake in the final layer of buttercream and allow to set in the fridge for an hour. Carefully pour your room temperature white chocolate ganache over the cake and allow to drip down the sides.
Decorate with various toppings.
For the cake
380 g butter
400 g caster sugar
2 vanilla pod
560 g pastry flour
35 ml baking powder
160 ml water
160 ml milk
250 g white chocolate chips
blue food colouring
For the caramel
125 ml heavy cream
35 g unsalted butter
5 ml vanilla paste
150 g granulated sugar
30 ml light corn syrup
30 ml water
For the Swiss buttercream
9 egg whites
220 g superfine sugar
225 g unsalted butter, softened but cool
5 ml vanilla paste
200 g white chocolate, melted
blue gel food colouring
For the white chocolate ganache
225g white chocolate
125ml pure cream
Lindt white chocolate
toasted coconut flakes
simple syrup (1 part water and 1 part sugar dissolved)