Preparation

• 1
  To Make the orange curd:
• 2
  You will need to make this before baking the cake. First, tip the sugar into a pyrex bowl.
• 3
  Beat the eggs in a separate bowl, add the juice and finely grated zest of the orange and then pour over the sugar and stir together.
• 4
  Cut the butter into small pieces and add to the mixture. Place the bowl over a pan of barely simmering water, not touching the water, and stir frequently until the butter has melted and the mixture has thickened, for 20-25 minutes.
• 5
  Allow to cool to room temperature and then stir, cover and allow to chill in the fridge.
• 6
  To make the sponge cake:
• 7
  Preheat the oven to 170 degrees or 155 degrees fan oven. Lightly grease, and line two 21cm circular cake tins with greaseproof baking paper.
• 8
  Sift the flour and baking powder into a large bowl and stir in the sugar. Cut the butter into small pieces, beat the eggs in a separate bowl, and add both to the bowl. Stir in the finely grated zest of 2 oranges and 5-6 teaspoons of orange juice.
• 9
  Whisk all the ingredients together really well. Spoon the mixture into the prepared tins, making sure that they are level, and bake for about 30 minutes. Carefully turn the cakes out onto a rack and allow to cool.
• 10
  To Make the white chocolate buttercream:
• 11
  Break the chocolate into small pieces and place in a pyrex bowl over a pan of barely simmering water. Stir until smooth and melted, then remove from the heat and allow to cool for 15 minutes, stirring occasionally.
• 12
  Cut the butter into small pieces, sift the icing sugar and then beat together until thoroughly combined. Add the melted white chocolate and 2 tablespoons of milk and beat again until you have a smooth buttercream.
• 13
  To assemble the cake, spoon the orange curd on the top of one sponge cake and spread evenly. Spread some of the buttercream evenly on the top of the other sponge cake to cover it, and then place this cake on top of the other, sandwiching the curd.
• 14
  Pipe the remaining buttercream on top of the cake, add decorations if required and then allow to set.