For the filling:
For the filling, stir together the mascarpone, quark and icing sugar until smooth. Let the espresso cool, combine it with the Amaretto and refrigerate the mixture until you’re ready to use it.
Preheat the oven to 180°C top/bottom heat. Line a springform pan (16 cm diameter) with parchment paper.
Separate the eggs. In a bowl, beat the egg whites with 1 pinch salt until stiff while gradually drizzling in half the sugar. Beat together the egg yolks and remaining sugar for about four minutes until you have a creamy, light-coloured mixture.
Sift together the flour, cocoa powder, starch and baking powder. In two batches, fold the egg whites into the egg yolk mixture. Sift the flour over the egg mixture, also in two batches, and carefully but quickly fold in. Transfer the mixture to the prepared springform pan and bake it in the preheated oven for 30 to 40 minutes until golden-brown. Test with a toothpick to determine when the cake is done.
Remove the cake from the oven, let it cool for 5 to 10 minutes and carefully loosen it from the pan using a small, sharp knife. Let it cool completely on a wire rack and cut it in half horizontally. Soak the two halves with the cold espresso-Amaretto mixture.
Place the first half on a cake platter and spread the top with one third of the mascarpone cream. Dust with cocoa powder. Place the second cake half on top and again spread the top with one third of the cream. Cover the sides of the torte with a thin layer of the cream and refrigerate for about 30 minutes. Remove the torte from the fridge, spread with the remaining cream and smooth out the surfaces.
In the meantime, make the chocolate shavings. Melt 150 g milk chocolate couverture in a bain marie. Using a rubber spatula, spread a thin, layer of melted chocolate onto a non-coated baking sheet or marble pastry board and smooth out the surface. Keep the baking sheet in a cool place until the chocolate has almost completely hardened, then use a ceramic scraper to make chocolate curls and refrigerate.
Decorate the torte with the chocolate curls and dust with cocoa powder. It’s best served cold.