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Royal recipe: Gâteau Opéra

Gâteau Opéra from the 'Royal Teas' cookbook
Gâteau Opéra from the 'Royal Teas' cookbook ©

This is a showstopper of a cake, soaked with coffee syrup and layered with chocolate ganache and coffee buttercream. Be warned, a little goes a long way, and the more precise you can be in assembling it, the better the final result will look!

Gâteau Opéra from the 'Royal Teas' cookbook

Gâteau Opéra from the 'Royal Teas' cookbook ©


For the joconde sponge sheets:

2 free-range eggs
60g (½ cup) icing sugar
60g (½ cup) ground almonds
25g (2 tablespoons) plain flour
20g (2 dessert spoons) unsalted butter, melted
175g (6oz) free-range egg whites (approximately 6 egg whites)
40g (3 tablespoons) unrefined caster sugar

For the chocolate ganache:

350g (12oz) dark chocolate (54% cocoa solids)
350ml (1½ cups) whipping cream

For the coffee buttercream:

3 free-range eggs
325g (12/3 cups) unrefined caster sugar
500g (2¼ cups) unsalted butter, diced and softened
6½ tablespoons water
Coffee extract to flavour

For the coffee soaking syrup:

150ml (5/8 cup) fresh coffee
75g (1/3 cup) unrefined caster sugar
75ml (¼ cup) water


Electric mixer
2 × Swiss roll baking trays (39 × 24 cm/15 × 10")
Gold leaf
Palette knife
Electric thermometer or sugar thermometer
25 × 8cm/10 × 3" rectangular mould or frame (optional)


  1. Preheat the oven to 200ºC (400ºF, gas mark 6).
To make the joconde sponge sheets:
  1. Line the Swiss roll baking trays with baking paper and put to one side. In a bowl place the icing sugar, ground almonds, flour and whole eggs and beat together for about 10 minutes until the mixture is pale and aerated. Add the melted butter and mix in thoroughly.
  2. Using the electric mixer, whisk the egg whites and caster sugar together to form a stiff meringue. Fold the meringue carefully through the egg mixture then divide between the two Swiss roll trays and spread evenly. Bake until the sponge is golden brown or springs back to the touch (8 minutes). Allow to cool before releasing from the tray.
To make the chocolate ganache:
  1. Boil the cream and then pour directly on to the chocolate, whisking until smooth. Leave to one side covered with cling film.
To make the coffee buttercream:
  1. Place the whole eggs into the bowl of the electric mixer with the whisk attachment. Place the water and the sugar into a saucepan and bring to the boil until it reaches 120°C/250°F. Once the sugar solution has reached this temperature, start to whisk the eggs and pour the sugar solution slowly and carefully into the mixer as you whisk. Whisk until cool before slowly adding the softened butter. Once the butter is fully incorporated, add the coffee extract to your own personal taste.
To make the coffee soaking syrup:
  1. Mix the freshly made coffee with the water and sugar, and allow to cool.
To assemble the Gâteau Opéra:
  1. Cut the joconde sheets into 6 strips measuring the same dimensions as your rectangular mould (or if assembling freehand just cut the sponge into 6 evenly sized rectangles).
  2. Line a flat tray with baking paper and sit the mould on top. Place the first joconde sheet into the rectangular mould and soak generously and evenly with the coffee soaking syrup.
  3. Next spread a thin, even layer of chocolate ganache on to the soaked layer of sponge, followed by the next layer of joconde. Ensure that the sponge is pressed down on top of the ganache evenly and securely. Soak the next sponge with the syrup. Repeat the ganache step but using instead the coffee buttercream, spreading a layer the exact thickness of the previous layer of ganache. Repeat this entire process until you get to the last layer of joconde, alternating ganache with coffee buttercream. The last layer will be soaked with the coffee syrup only. See the image on this page for the finished effect you are aiming for!
  4. Place in the fridge and allow to firm for at least an hour.
  5. Once firm, remove the rectangular ring, using a hot dry knife to release the Gâteau Opéra from the edges of the mould. Place the cake on to a clean chopping board. Soften some of the remaining ganache in a microwave until it is a thick pouring consistency. Using a palette knife, spread the warmed ganache on the top of the opéra as thinly and evenly as you can. Return the gâteau to the fridge for the ganache to firm.
To portion and present:
  1. Trim the edges of the gâteau with a hot dry knife to ensure the edges are straight before using a ruler to mark out the portion size. Slice the cake into the marked portions again using a hot dry knife. The gâteau pictured on this page has been cut in to portions of 2.5 × 6 cm (1 × 2.5"), but you can be as generous as you like! Finally, place on your serving dish and decorate with gold leaf.