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Gateau Opera

/ Categories Tricks of the trade, Recipes, Behind the scenes / Author:

Gateau Opera

You will need a 20 x 20cm thin cake board.


Joconde Sponge
85g ground almonds
55g icing sugar
30g bread flour
3 whole eggs
1 egg yolk
2 egg whites
30g caster sugar
30g butter, melted

Coffee custard buttercream
150 ml milk
110g caster sugar
1 tbsp instant coffee granules or a shot of espresso
2 egg yolks
110g unsalted butter – room temperature
110g salted butter – room temperature

Chocolate Ganache
350g plain chocolate
250g double cream
1tsp glucose

Coffee Syrup
300g granulated sugar
300ml water
3tsp instant coffee

Chocolate Mirror Glaze
110ml water
210ml sugar
65g double cream
10g gelatine (bronze)
50g dark chocolate
65g cocoa powder


  1. To make the sponge, combine the ground almonds, icing sugar and flour in medium size bowl. Gradually add the whole eggs and continue to beat the mixture for 5 minutes at high speed. Mix in the egg yolks at a medium speed until well combined .Whisk the egg whites to soft peaks. Whisk in the sugar. Add the melted butter and fold to combine. Fold the whisked egg whites into the egg mixture. Spread the mixture out to about 5mm onto a silpat, keeping within the red border and bake at 200˚C for 10 minutes.
  2. To make the buttercream - place the milk and half of the sugar and the coffee granules in a small pan and heat until the mixture steams. Place the egg yolk in a bowl with the remaining sugar and combine well. Gradually combine the hot milk into the sugar and yolk mixture. Rinse the pan out and return the mixture to the pan. Cook the custard over a medium-low heat until thickened. It should coat the back of a wooden spoon. Strain the custard to remove any egg threads and allow to cool. Beat the butter until soft and creamy. Whisk the cooled custard into the butter, a spoonful at a time. Store at room temperature until needed.
  3. Next make the ganache by chopping the chocolate into 1cm pieces and put into a heatproof bowl with the glucose. Pour the cream into a small saucepan and bring to a simmer over a medium heat. Slowly pour the hot cream over the chocolate pieces and stir gently until the chocolate has melted and the mixture is well combined. Allow the mixture to set up at room temperature.
  4. To make the coffee syrup, place the sugar and water into a saucepan and heat gently until the sugar has dissolved completely, bring to the boil. Boil for 2 minutes, add the coffee, remove from the heat, divide into 3 pots and allow to cool.
  5. To assemble, cut the joconde into 3 squares of 18cm x 18cm. Brush the bottom layer with a one third of the coffee syrup until the cake is soaked but not soggy. Spread with the coffee buttercream. Place the second layer of cake on top of the buttercream and brush with another third of syrup. Spread with about two-thirds of the chocolate ganache. Place the last layer of cake on top, brush with syrup and spread with a thin layer of ganache. Make sure this layer is very smooth, then chill in the fridge for at least 30 minutes.
  6. While waiting for the cake to chill, you will need to make the mirror glaze. To do this soak the gelatine in cold water. Bring the water, sugar and cream to a boil. Stir the softened gelatine into the hot mixture. Allow to cool down for 5 minutes. Pour the hot cream mixture over the chocolate and mix to incorporate. Stir the chocolate mixture into the cocoa powder. Use at 28 – 32 C (30 is ideal) Pour the chocolate glaze evenly over the cake and allow to set in the fridge for about 15 minutes.
  7. Finish the cake by piping the word ‘Opera’ on the top.

Author: Ailie Bishop


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