Method

• 1.
  Preheat oven to 90°C. Line 2 large oven trays with baking paper.
• 2.
  For the candied orange, place orange slices in a single layer over the prepared trays and dust liberally with icing sugar. Place in oven and dehydrate for 5-6 hours until slices are candied and dry. Remove from oven and stand until completely cool. Transfer to a lined airtight container and seal until ready to use.

• 3.
  Increase oven temperature to 160°C. Grease four 20cm cake pans, and line with baking paper, double lining the base.
• 4.
  To make the cakes, place the chocolate, butter, sugar, cream and vanilla in a medium saucepan over medium heat and stir until smooth. Transfer to a large heatproof bowl and cool, then stir in eggs until combined.
• 5.
  Add the zest and both the flours and stir until combined and smooth. Divide the mixture among prepared pans. Tap each pan firmly on the bench to knock out any air pockets.
• 6.
  Bake for 40-45 minutes until a skewer inserted into the centre comes out clean. Remove cakes from oven and cool in pan for 20 minutes, then invert onto wire racks to cool completely. Once cooled, trim tops from the cakes so they are level. Set aside.
• 7.
  Meanwhile, to make the white chocolate and orange sauce, place the chocolate in a large heatproof bowl over a medium saucepan of simmering water. Place cream in a separate saucepan over medium heat and bring to the boil. Pour hot cream over the chocolate and stir continuously, slowly heating the mixture, until the chocolate has melted and ganache is smooth. Stir through orange zest. Set aside at room temperature to cool for 30 minutes.
• 8.
  Half-dip the candied oranges into the white chocolate sauce and place back on the oven trays until ready to use. Cover remaining sauce with plastic wrap until ready to use.
• 9.
  For the white chocolate buttercream, place the butter and icing sugar in the bowl of a stand mixer fitted with the paddle attachment and beat on high speed until light and fluffy. Reduce speed to low and gradually beat in slightly cooled white chocolate until combined. Set aside.
• 10.
  To assemble, place one cake on a serving plate. Spread with a 1cm layer of buttercream, then top with the second cake. Repeat layering until you reach the final cake. Spread the buttercream over the top and side of the cake to create a crumb coat, and chill for 30 minutes to set. Using the remaining buttercream, frost the entire cake with a thick layer, then use the tip of a 3cm wide palette knife to make long, even strokes from the base to the top of the cake, creating long vertical lines in the buttercream. Chill for 5-10 minutes to set. Top with candied oranges and serve with the remaining white chocolate and orange sauce.