For the joconde:
vegetable oil, for greasing
225g ground almonds
225g caster sugar
5 large eggs
5 large egg whites
50g plain flour, sifted
35g unsalted butter, melted
finely grated zest of 2 lemons
25g pistachio paste
½ tsp almond extract
leaf green food colouring
For the French buttercream:
6 large egg yolks
190g caster sugar
300g unsalted butter, softened
1 tsp vanilla bean paste
10 firm raspberries
For the syrup:
juice of 1 lemon
2 tbsp water
For the decoration:
200g dark chocolate chips, 54% cocoa solids
freeze dried raspberries, for dusting
5 firm raspberries, halved
Step 1 – Heat the oven to 210C/Fan 190C/gas 7. Line two 40cm x 25cm baking sheets with non-stick baking paper and lightly grease with vegetable oil.
Step 2 – For the joconde, whisk the ground almonds, 150g of the caster sugar and the eggs together to ribbon stage.
Step 3 – In a separate bowl, whisk the egg whites and the remaining 75g of caster sugar together, to a stiff meringue.
Step 4 – Gently fold the meringue mixture into the almond mixture.
Step 5 – Sieve the flour over the top of the mixture and gently fold in.
Step 6 – Finally, gently fold in the melted butter.
Step 7 – Divide the mixture into 2 bowls. Fold the grated lemon zest into one bowl of mixture.
Step 8 – Fold the pistachio paste, almond extract and enough green food colouring to create a pistachio colour into the second bowl of mixture.
Step 9 – Pour the mixture into the lined tins (one in each tin) and level out with a palette knife.
Step 10 – Bake for 9-11 minutes until springy, but firm to the touch. Remove from the oven and leave to cool on a wire rack.
Step 11 – For the French buttercream, tip the eggs yolks into the bowl of an electric food mixer and whisk until pale, thick and creamy.
Step 12 – Tip the sugar and water into a pan and boil to softball stage (116C). Remove from the heat and with the whisk still running, very slowly pour the sugar syrup over the whisked egg yolks. Continue whisking until the mixture is cool to touch.
Step 13 – Once the egg and sugar mixture is cold, whisk in the softened butter, bit by bit until the mixture thickens.
Step 14 – Transfer ¾ of the buttercream into a separate bowl and fold in the vanilla paste. Set aside.
Step 15 – With the whisk still running on low, add the raspberries to the remaining buttercream and whisk until they are broken up but not mushy. Set aside.
Step 16 – For the lemon syrup, tip the lemon juice, water and sugar into a pan and bring to the boil, stirring until the sugar dissolves. Remove from the heat and leave to cool.
Step 17 – To assemble, lightly grease and line a 17cm square cake tin and line with non-stick baking paper. Turn out the sponges, remove the baking paper and cut two 17cm squares from the lemon sponge and two 17cm squares from the pistachio sponge.
Step 18 – Melt 50g of the chocolate and spread one side of one lemon sponge very thinly with chocolate. Place the sponge, chocolate side down in the base of the lined cake tin and brush the top lightly with lemon syrup.
Step 19 – Spread 1/3rd of the vanilla buttercream over the sponge and top with a pistachio sponge. Brush with lemon syrup.
Step 20 – Spread all the raspberry buttercream over the sponge and top with the second pistachio sponge. Brush with lemon syrup.
Step 21 – Spread another 1/3rd of the vanilla buttercream over the pistachio sponge and top with the remaining lemon sponge. Brush with lemon syrup. Chill in the fridge for 30 mins. Spoon the remaining buttercream into a piping bag fitted with a ribbon nozzle.
Step 22 – For the chocolate decoration, temper the chocolate by melting the remaining chocolate in a bowl set over a pan of simmering water to 50C. Remove the bowl from the heat. Pour 2/3rd of the chocolate onto a marble slab and cool to 28C. Return the cooled chocolate to the bowl and stir until the temperature reaches 32C.
Step 23 – For the chocolate decorations, cut a rectangular piece of acetate measuring 15cm x 6cm. Spread some of the tempered chocolate over the acetate and leave until beginning to set. Score into long triangle shapes as per the template attached. Bend the acetate sheet lengthways into a half moon curve and leave to set inside 2 chefs ring, so the triangles set curved.
Step 24 – Turn the cake out of the cake tin. Trim the edges and cut the cake into 9 square cakes measuring 5cm x 5cm. Tip the freeze dried raspberries into a sieve and dust the tops of the cakes lightly with raspberry powder.
Step 25 – Pipe a wavy ribbon of buttercream diagonally across the top of each of the 9 cakes. Peel the acetate away from the set chocolate and spray with the gold shimmer. Decorate the top of each cake with a curved chocolate triangle and half a fresh raspberry.