Gateau Opera

Ingredients

• 150 g ground almonds
• 150 g icing sugar
• 4 medium eggs
• 40 g plain flour
• 4 egg whites
• 25 g caster sugar
• 30 g unsalted butter, melted and cooled
• 200 ml strong hot espresso
• 80 g caster sugar, for the syrup
• 100 ml water
• 3 egg yolks
• 120 g caster sugar, for the buttercream
• 40 ml water, for the buttercream
• 250 g soft unsalted butter
• 2 tbsp instant espresso powder dissolved in 1 tbsp hot water
• 200 g dark chocolate, 70 percent, chopped
• 200 ml double cream
• 30 g unsalted butter, for the ganache
• 150 g dark chocolate, for the glaze
• 25 ml flavourless oil

Before you cook

• Line two large flat baking trays with baking paper.
• Sift the ground almonds with the icing sugar into a bowl.
• Separate the 3 egg yolks for the buttercream and leave them in the bowl of a stand mixer.
• Cut a stiff card template 30 cm by 20 cm to trim the sponge later.

Steps

1. Heat the oven to 200C fan.
2. Whisk the ground almond and icing sugar mixture with the 4 whole eggs on high speed for eight minutes, until tripled in volume and pale.
3. Sift the plain flour over the top and fold it in gently with a spatula.
4. In a clean bowl, whisk the 4 egg whites to soft peaks, then rain in the 25 g caster sugar and whisk to a firm glossy meringue.
5. Fold a third of the meringue into the almond batter to loosen it, then fold in the rest in two more additions.
6. Fold in the 30 g melted butter last, stopping the moment it disappears.
7. Divide the batter between the two trays and spread each one to an even 5 mm thickness.
8. Bake for 8 to 10 minutes, until the surface springs back and the edges are lightly coloured.
9. Slide the sponges off the trays onto a wire rack and peel the paper away while still warm.
10. Boil the 100 ml water with the 80 g caster sugar until the sugar dissolves, then stir in the hot espresso and set aside to cool.
11. Bring the 120 g sugar and 40 ml water to 118C in a small pan, using a thermometer.
12. Whisk the 3 yolks on medium speed and pour the hot syrup down the side of the bowl in a thin steady stream.
13. Keep whisking for eight minutes until the bowl is cool to the touch and the mixture is thick and pale.
14. Add the 250 g soft butter a cube at a time on medium speed, then beat in the dissolved espresso powder.
15. Heat the 200 ml double cream until it steams, pour it over the 200 g chopped chocolate and leave for two minutes.
16. Stir the ganache from the centre outwards until smooth, then beat in the 30 g butter and leave to thicken to a spreadable paste.
17. Trim both sponges with your card template, giving you three equal rectangles in total.
18. Lay the first sponge on a board and brush it generously with coffee syrup.
19. Spread half the coffee buttercream over it in an even layer.
20. Add the second sponge, press it down lightly and brush it with syrup.
21. Spread two thirds of the ganache over that layer and level it with a palette knife.
22. Add the third sponge, brush with the last of the syrup and spread the remaining buttercream on top as smoothly as you can.
23. Chill the cake flat for one hour until firm.
24. Melt the 150 g glaze chocolate with the oil, let it cool to just warm, then pour it over the cake and tilt to cover.
25. Chill for 30 minutes, then trim 1 cm from each edge with a hot dry knife to expose the layers.
26. Cut into 12 rectangles, wiping and reheating the knife between each cut.