Matcha Opera Cake

To make the matcha sponge

1. Preheat the oven to 350F (180C).
2. Combine the ground almonds, matcha powder, icing/confectioners’ sugar and egg yolks in the bowl of a stand mixer with a whisk attachment (or use a mixing bowl and a hand-held electric whisk). Add the flour and beat until incorporated.
3. In a separate bowl whisk the egg whites to soft peaks using a hand-held electric whisk, then increase the mixing speed and slowly add the sugar, whisking until you have a stiff glossy meringue mixture. Carefully fold this into the matcha mixture followed by the melted butter.
4. Spread the cake batter very evenly onto the two prepared baking pans right to the edges. Bake in the preheated oven for 8–10 minutes until just cooked and a skewer inserted comes out clean.
5. Turn the baking sheets upside-down onto a wire cooling rack and peel off the paper from the bottom of the sponges. Leave to cool on a wire rack until required.

To make the pistachio buttercream

1. Drop the sugar in a saucepan with 65 ml (1/4 cup) water over medium heat with the sugar thermometer inside and bring to the boil. In the meantime, put the egg whites into the bowl of a stand mixer fitted with a whisk attachment.
2. When the temperature of the sugar gets to around 244F (118C), turn the mixer on and start to beat the egg whites.
3. When the temperature of the sugar reaches 250F (121C) and the egg whites have just reached soft peak stage (take care not to overwhip), reduce the speed of the mixer and very carefully pour the hot sugar syrup down the side of the bowl, being careful not to get any syrup onto the whisks or burn yourself.
4. Increase the speed of the mixer and continue to beat the egg whites for 5 minutes until the mixture has cooled to warm.
5. Gradually add the diced butter and mix until fully incorporated.
6. Lastly, add the pistachio paste and mix in well. Cover the buttercream with plastic wrap and refrigerate until required.

To make the matcha ganache

1. Pour the cream in a saucepan with the matcha powder. Stir together and bring to the boil.
2. Remove from the heat and strain the milk through a fine-mesh strainer into another bowl containing the chopped white chocolate. Stir gently until the chocolate has melted to form a smooth ganache. Set aside.

To make the soaking syrup

1. Place all the ingredients in a saucepan with 75 ml (1/3 cup) water and bring just to the boil, stirring to dissolve the sugar. Set aside until required.

To assemble the cake

1. Trim the two sponges into four equal rectangles and put one of the rectangles on a large piece of non-stick baking parchment.
2. Melt the dark/bittersweet chocolate either in the microwave or in a heatproof bowl set over a pan of barely simmering water, making sure the base of the bowl does not touch the water.
3. Using a pastry brush, apply the melted chocolate to the first layer of sponge. Allow this to set firm, then turn over, this will form the base of your opéra.
4. Brush the top of the sponge liberally with the soaking syrup.
5. Using an angled palette knife, next spread over an even layer of pistachio buttercream.
6. Put the second piece of sponge on top, brush with more soaking syrup and then use the palette knife to spread over an even layer of matcha ganache.
7. Put the third piece of sponge on top, brush with syrup and add another layer of buttercream.
8. Add the fourth and final piece of sponge on top and press down lightly with the back of a tray to compress the layers. Brush the top with the remaining melted dark/bittersweet chocolate.
9. Transfer the whole cake to the fridge to set for around 30 minutes; meanwhile make the glaze for the top.

To make the pistachio glaze

1. Combine the cream, liquid glucose, matcha powder and pistachio paste in a saucepan and bring just to the boil. Remove from the heat, squeeze out the excess liquid from the gelatine and stir in. Pour over the white chocolate and stir until melted and combined into a smooth, glossy glaze.
2. Retrieve the cake from the fridge and put on a wire rack over a tray. Pour the warm glaze over the top of the dessert. Smooth over with a palette knife/metal spatula to achieve a nice clean finish and return to the fridge for 20 minutes for the glaze to set.

Serving

1. Trim away the edges of the opera using a serrated knife warmed in a jug/pitcher of hot water. You can then serve the cake whole or cut into neat slices.