Gâteau Opéra

Sat, Jun 13, 2015, 01:00

   
  • Makes: 1
  • Cooking Time: 120 mins
  • Course: Dessert
  • Cuisine: French

Ingredients

  • Almond sponge:75g ground almonds
  • 50g icing sugar
  • 1 large egg
  • 2 egg yolks
  • 65g flour
  • 50g caster sugar
  • 4 large egg whites
  • Coffee soaking syrup for sponge:
  • 150ml water
  • 15g instant coffee powder
  • 20g sugar
  • Ganache:
  • 250ml cream
  • 200g 53% cocoa chocolate
  • Coffee buttercream:
  • 60ml water
  • 230g sugar
  • 30g glucose
  • 2 egg yolks
  • 2 eggs
  • 300g soft butter
  • 60ml very strong coffee, cold
  • Chocolate glaze: 55g cream
  • 65g 70% chocolate
  • 40g sugar
  • 15g cocoa powder
  • 50ml water

Method

Preheat an oven to 230 degees/gas 8.

For the sponge: Mix the ground almonds, icing sugar, egg and egg yolks in a small bowl with a whisk until pale. Fold in the flour.

Using an electric mixer, whisk the egg white and caster sugar to stiff peaks. Fold into the almond mixture.

Line two 12in/30.5cm square tins with parchment paper (if you only have one tin, don’t worry – it cooks quickly and you can reuse the tin).

Divide the mix between the two tins and spread evenly – this will be wafer thin.

Bake in the preheated oven for five to six minutes. Allow to cool. When cool remove from the tin and wrap in cling film.

For the coffee syrup: Dissolve the coffee and sugar in the water over a gentle heat whisking all the time, then bring to the boil. Remove from the heat and allow to cool.

For the ganache: Boil the cream and pour it over the chocolate, whisking until smooth; allow to cool. Place the ganache in a bain marie to soften before using.

For the coffee buttercream: In a saucepan over a medium heat bring the first three ingredients to 121 degrees Celsius (this is called pâté à bombe). Using an electric mixer with a K beater attachment mix the eggs and the egg yolks until they thicken, then very slowly add the pâte à bombe, and continue mixing until it cools. Then very slowly add the butter and mix until smooth. Add the coffeeat the end.

For the chocolate glaze: Bring the cream to the boil, then pour it over the chocolate. In a separate saucepan bring the sugar and water to the boil, add the cocoa powder, whisk it in and cook it until it comes together. Pour the warm cocoa mix over the melted chocolate and cream. Bring to room temperature by placing in a bain marie.

To assemble: set a quiet time for this. Have all the ingredients at room temperature.

Line the base and sides of a rectangular 4 in x 10 in tin (10cm x 25cm) with parchment paper, leaving an overlap so you will be able to grip it and remove the cake from the tin when you’re finished.

Halve each of your square bases, and trim them so that each layer fits snugly into the rectangular tin. This needs to be very precise to stop any leaks occurring.

Put one layer of sponge in the rectangular tin. Brush it with the coffee syrup, making sure it is well soaked but not wet. Spread one third of the ganache over the first layer of sponge, making sure it goes right into the edges and corners. Place in the fridge to set.

Next, spoon a third of the coffee butter cream over the chocolate ganache; again, spread evenly, making sure it goes right into the edges and corners.

Then place the next layer of sponge on top, brush it heavily with the coffee syrup, making sure it is soaked but not wet. Spread a third of the ganache on top, evenly, making sure it goes right into the edges and corners. Place in the fridge to set. Spread another layer of butter cream on top again, as before. Repeat these layers once more. Finally, top with the last layer of sponge, soak it lightly with the syrup and place in the fridge for 15 minutes to firm up.

Pour the chocolate glaze over the top, allowing it to flow evenly so that the top is evenly coated. Place in the fridge until required.

To serve, grip the parchment paper and carefully remove the cake to a serving plate.