Mix the raspberries, water, sugar and lemon juice and stir with a wooden spoon, bashing up the raspberries until they have mushed down and the sugar has dissolved.
Place in a bowl and allow to cool - this can be made a few days in advance.
Combine the seedless raspberry jam and the raspberries. Cook over a medium heat and stir until thickened. Sift the compote to remove all of the seeds and cover with clingfilm, pressing it to the surface of the compote so a skin doesn't form. This can be made a few days in advance.
***Chocolate Sponge Cake***
Preheat the oven to 180C (Fan Oven), line two baking sheets with greaseproof paper. Sift the flour with the cocoa powder.
Whip the egg whites in the bowl of stand mixer until they hold a soft peak. Add the caster sugar and whisk until firm and glossy.
Add the egg yolks and whip until smooth, about 5 seconds.
Gradually add the dry ingredients and gently fold in with a flexible spatula.
Spoon the pastry batter in a piping bag fitted with a 1cm nozzle, or cut a 1cm hole in a disposable piping bag.
Pipe neat rows on each of the prepared baking sheets, you can spread the batter with a spatula, but piping it gives the most even results.
Bake each sheet for 10-12 minutes until just firm to the touch and it springs back.
Rotate the sheet halfway through baking and transfer to a cooling rack.
Mix the sugar with the water in a small saucepan with a heavy base. Stir until the sugar dissolves. Bring to a boil and cook until it registers 118C on a thermometer.
In the bowl of a stand mixer, mix the egg yolks and the whole egg at a low speed. When the sugar syrup is ready, increase the speed of the mixer to high and carefully pour in the sugar syrup, whisk until the mixture cools to room temperature, around 5-8 minutes.
Finely chop the chocolate, place it in a bowl set over a saucepan and melt until it reaches 45C, then remove from the heat.
Whip the cream until it holds a firm peak. Mix the chocolate into the egg mixture and stir until it is fully combined.
Beat a third of the cream into this mixture to lighten it. Add the remaining cream and mix until smooth and an even colour.
Finely chop the chocolate, place it in a medium bowl over a pan of water and melt. Remove from the heat and stir until smooth.
Spread the melted chocolate over one of the sponge cakes and let it set. Sift confectioners sugar over the top, place the round cake ring on the top and cut off the excess cake. Cut out the other cake. Clean the cake ring and line the sides with a strip of cooking acetate. Then place the plain sponge in the bottom. Brush with raspberry compote.
Spread half the mousse on top and smooth with an offset spatula, place the chocolate covered cake on top and spread with raspberry syrup, add the remaining mousse and smooth it with an offset spatula.
Freeze until the mousse sets, at least 2 hours, place the cake on a cake rack over a tray and pour the raspberry compote over the cake. Place the cake in the fridge and allow the excess compote to drip off.
Use the remaining glaze to coat the fresh raspberries so they have a shine to them.
After about 15 minutes the glaze should have stopped dripping, place the cake on a cake board or plate. Decorate the edge of the cake with freeze-dried raspberry powder and or cacao nibs.
Decorate the top of the cake with the chopped pistachios, raspberries, gold leaf and royal icing flowers in any design you like.