Pistachio Joconde (Biscuit aux Pistaches)
Mix the almond paste and the pistachio paste together in a mixer bowl
Add the whole egg, egg yolks, and egg whites and beat until thick and pale
Make french meringue in a separate bowl (see the chocolate joconde instruction)
Mix some meringue into the batter, fold well
Add the sifted cornstarch, fold well
Add the melted batter
Lastly, fold in the rest of the meringue
Spread the batter into half-sheet pan (you might end up with less volume if you overmix the batter and might want to use 9x13" pan)
Bake in the oven at 230C for 5-6 minutes
Blackberry Mousse
Whip the heavy cream to a soft peak and set aside
Heat the blackberry puree and bring it to a simmer, take it off the heat
Add the gelatin leaves or melted powdered gelatin, mix well
Let the black berry mixture cool on an ice bath, stirring once in a while
Once cooled, add the liqueur
Fold in the italian meringue
Lastly, fold in the whipped cream
Pour into plastic-lined 7" square cake ring or baking pan and put it in the freezer
Once frozen, cut out circles smaller than the cake ring you are using to assemble the cake
Italian Meringue
Mix together the sugar and the water in a saucepan and bring it to 118-120C
When the temperature is close, start whipping the egg whites
Once the sugar syrup is ready, pour the syrup into the egg white with the mixer still running
Whip until stiff and shiny
Pistachio Mousse
Whip the heavy cream until soft peak and set aside
Combine milk, pistachio paste, and vanilla bean seeds in a saucepan, bring to a simmer
Meanwhile, whisk the egg yolks and the sugar until pale
Once the milk mixture is ready, temper the yolk with the milk and return it back to the saucepan
Stirring constantly, bring the mixture to 84C under low heat
Add the gelatin and mix well
Strain the mixture and let cool on an ice bath
Fold in the whipped cream
Soaking syrup
Mix all ingredients
To Assemble
Assemble the cake upside down.
Brush the pistachio joconde with the soaking syrup
Place an acetate sheet in the bottom of a sheet pan and place the cake rings on top
Pipe some pistachio mousse
Place the blackberry mousse in the center
Pipe more mousse almost to the top of the ring
Place the pistachio joconde at the top, pushing it down slightly so that it is the same level with the mousse.
Freeze overnight and unmold (the bottom is now the top part)
Glaze with neutral glaze and decorate with blackberry and pistachio pieces