Opéra Cake

Opéra Cake

Adapted from Le Cordon Bleu Home Collection (Chocolate)

This elegant chocolate-covered cake, whose invention is attributed to the Dalloyau pastry house, consists of layers of biscuit soaked in coffee syrup and garnished with butter cream and chocolate ganache.

Preparation time: 2 hours + refrigeration
Serves 4 to 6

Ingredients

Almond sponge

• 75 grams (2 ½ ounces) icing sugar
• 2 ½ tablespoons flour
• 75 grams (2 ½ ounces) almond powder
• 3 eggs
• 15 grams (1/2 ounce) unsalted butter, melted and cooled
• 3 egg whites
• 1 tablespoon caster (superfine) sugar

Ganache

• 200 grams (6 ½ ounces) superior-quality dark chocolate, finely chopped
• 120 ml (4 fl ounces) milk
• 110 ml (3 ¾ fl. ounces) thick cream
• 50 grams (1 ¾ ounces) unsalted butter, softened)

Coffee syrup

• 1 ½ tablespoons sugar
• 1 ½ tablespoons instant coffee
• 90 ml (3 fluid ounces) water

Butter cream

• 70 grams (2 ¼ ounces) caster (superfine) sugar
• 1 egg white
• 1 tablespoon instant coffee
• 100 g (3 ¼ ounces) unsalted butter, softened

Directions

1. To prepare the sponge layer, first, preheat the oven to 220 degrees C (425 degrees F). Line a 20 x 30 cm (8 x 12 inches) baking pan with parchment paper. In a large bowl, sift together the flour and icing sugar, then add the powdered almonds. Mix well. Add eggs, one at a time, and beat until pale. Add the melted butter.

1. Beat the egg whites until stiff, then gradually add sugar and continue  beating until stiff peaks are obtained.

1. Add 1/3 of the beaten egg whites to the batter, mixing well, then incorporate the remainder, folding until just combined. Pour onto the baking tray and spread evenly. Bake for 6 to 8 minutes, or until golden and springy when touched. Loosen the edges with a knife and carefully turn out onto a wire rack covered with a sheet of parchment paper. Allow to cool.

1. Place finely chopped chocolate in a heatproof bowl and set aside. Bring milk and 30 ml (1 fluid ounce) of the cream to a boil. Pour the hot liquid onto the chocolate. Wait 30 seconds, then add the butter and mix until smooth. Let cool until a spreadable consistency is obtained.

1. To prepare the coffee syrup, place sugar and 90 ml (3 fluid ounces) of water in a pan and stir until dissolved. Bring to a boil and add coffee.

1. To prepare butter cream, place sugar and 3 teaspoons of water in a heavy skillet and make a sugar syrup, i.e. stir until sugar is completely dissolved, then boil, without stirring, until syrup reaches soft-ball stage, between 116  and 118 degrees C (214 – 244 degrees F).

1. Beat the egg white until soft peaks are obtained. Continue beating while incorporating the hot syrup. Beat until mixture is cold. Dissolve instant coffee in 1 teaspoon of boiling water, cool and add to butter. Add one half of the egg-white mixture and beat well, then gently fold in the remainder until well combined.

1. Using a sharp knife, divide the sponge into three equal sections and carefully peel off parchment paper from sections. Each should be 10 x 20 cm (4 x 8 inches). Soak the first section with one-third of the coffee syrup, then spread over it half of the butter cream. Place the next section of sponge on top, then soak with coffee syrup and spread with half of the ganache. Place the last section on top, soak with remaining syrup and spread with the rest of the butter cream, taking care to smooth the surface. Chill until butter cream firmly set.

1. Melt the rest of the ganache over a pan of very hot water. Bring the remaining cream to the boiling point and incorporate into ganache. Allow to cool until a smooth, spreadable consistency is obtained and spread over top of cake.