CHOCOLATE, ORANGE AND CARDAMOM OPERA CAKE

Posted By: Emily
SEPTEMBER 06, 2016

Serves: 8-12
Total Time: 4 Hours * Active Time: 2 Hours
Courtesy of: John W.

Ingredients

BISCUIT SPONGE

  • 4 Eggs
  • 100g Ground Pistachios
  • 50g Ground Almonds
  • 150g Icing Sugar
  • 45g Flour
  • 5 Eggs Whites
  • 25g Sugar
  • 40g Unsalted Butter
    • Melted

GANACHE

  • 100ml Milk
  • 4 Cardamom Pods
    • Bruised
  • 200g Dark Chocolate
    • Roughly Chopped
  • 20g Unsalted Butter
    • Room Temperature

SOAKING SYRUP

  • 60g Sugar
  • 60ml Water
  • 4 Cardamom Pods
    • Bruised
  • 100ml Orange Juice

ORANGE BUTTERCREAM

  • 75g Unsalted Butter
    • Room Temperature
  • Zest from 1 Large Orange
  • 150g Icing Sugar
  • 1 Teaspoon Fresh Orange Juice

MIRROR GLAZE

  • 1g Gelatin
  • 120g Golden Caster Sugar
  • 60ml Water
  • 1 Tablespoon Golden Syrup
  • 75g Cocoa Powder
  • 60ml Single Cream

Directions

Grease and line 2 jelly roll pans (8×12).
Preheat oven to 375 degrees.

BISCUIT SPONGE

  1. In a mixing bowl, combine the eggs, ground pistachios, almonds, icing sugar and flour and beat until well combined and smooth.
  2. In another bowl, whisk the egg whites to stiff peaks and then add sugar in three incorporations, whisking well after each addition until the sugar is dissolved.
  3. Scoop the meringue on top of the egg and nut mixture and pour on the melted butter.
  4. Gently fold together until just incorporated, trying not to expel too much air. The mixture will be runny.
  5. Divide the mixture between the two pans and bake for 12-15 minutes or until lightly golden in color and the sponge springs back when pressed lightly.
  6. Allow to cool completely before removing from the tins.

GANACHE

  1. Place the milk in a saucepan with the bruised cardamom pods and set over a high heat.
  2. When mixture begins to steam, remove from the heat and allow the cardamom to infuse the milk for about 10 minutes.
  3. Remove the pods and reheat the milk on medium-high until bubbles just begin to form around the edges.
  4. Place the chopped chocolate in a heatproof bowl and pour the hot milk over it.
  5. Allow the milk to heat the chocolate for about 30 second, then use a whisk to blend together to a smooth, glossy ganache.
  6. Whisk in the butter until it is well incorporated, then pour on to a large plate and set aside to cool.

SOAKING SYRUP

  1. Place the sugar, water and bruised cardamom pods in a saucepan and set over a high heat.
  2. Bring to a boil and boil for 3 minutes, then turn off the heat and leave it to cool slightly.
  3. Stir in the orange juice and allow to infuse.

BUTTERCREAM

  1. Place the butter and zest in a bowl and whisk until pale and smooth.
  2. Sift in the icing sugar and add the orange juice, beating slowly at first until it comes together and then whisking vigorously for at least 5 minutes.

ASSEMBLE

  1. Cut the two sponges so that you have two 20cm squares and two 10x20cm rectangles.
  2. Place one of the 20x20cm squares on a board and soak it well with some of the syrup using a pastry brush.
  3. Spread 2/3 of the ganache on to this first layer and chill for 20 minutes.
  4. Place the two rectangular pieces of sponge on top and soak well with some syrup.
  5. Spread the buttercream on top and chill for 20 minutes.
  6. Take the final square of sponge and soak it well with syrup and place the soaked side down on the buttercream.
  7. Spread the remaining ganache evenly over the top of the cake and chill in the freezer for 30 minutes.

MIRROR GLAZE

  1. Bloom the 1g gelatin per the box instruction.
  2. Heat the sugar, water and golden syrup in a small saucepan.
  3. Allow to boil for a minute or two and then remove from heat and whisk in the cocoa powder.
  4. Whisk in the cream, then return to a medium heat for a minute, stirring constantly and then remove from heat.
  5. Add the gelatin to the chocolate glaze and stir until dissolved.
  6. Pass the glaze through a sieve into a bowl and store in the fridge until needed.

FINISHING TOUCHES

  1. Pour the mirror glaze over the chilled cake so that it’s evenly on top. It’s okay if it drips down the side. Put back in the fridge for 20 minutes.
  2. When the mirror glaze has set, dip a very sharp knife into boiling water and dry quickly on a cloth.
  3. Slice a tiny amount from each edge to create nice defined layers.
  4. Repeat the knife-heating technique and cut the cake into 4 equal squares.
  5. Then cut each square in half to have slices.

Notes:
It’s important to get that final ganache layer very smooth before putting it to set in the fridge. Otherwise, the mirror glaze will pick up any bumpiness.