Use only the bottom and top of the dough. Whip the cream and sugar until stiff. Add the soaked gelatin, heated and at the gelling point, and the juice of one lemon. Spread about half of the whipped cream on the bottom layer. Sprinkle half of the chopped pistachios. Place the second cake layer on top. Divide the remaining cream in half. Spread one part on the top of the cake, dot with the second. Sprinkle with minced pistachios. Leave the cake to cool.