Line a springform pan with plastic wrap.
For the cake cream, cream butter with sugar. Mix in almonds, milk, whipped cream and yolks.
For the sponge cake, mix milk, rum and sugar. Briefly fold the biscuits through the milk-rum mixture and line the prepared springform pan with them: In the first step, line the bottom of the springform pan with whole biscotti, then place halved biscotti vertically along the edge.
Spread a layer of cream on top. Soak more biscuits and place them on top of the cream, spread this layer of biscuits again with cream and repeat this process until the cream is used up. Finish with soaked biscotti as the top layer. Cover the surface with plastic wrap.
Allow cake to set in refrigerator for at least 4 hours.
Meanwhile, for garnish, melt couverture according to package directions. Decorate sponge cake with chocolate coating according to taste. Allow to dry.
Whip the cream with cream stiffener and powdered sugar until stiff. Carefully remove the cake from the springform pan and spread with approx. 2/3 of the whipped cream. Press almond flakes all around the edge of the cake.
Fill the remaining whipped cream into a piping bag and pipe small “tuffs” onto the surface of the cake. Garnish with chocolate biscuits and almonds.