For the shortcrust pastry, mix 250 g all-purpose flour, 125 g butter (cut into small pieces), 60 g sugar, 1 pinch salt, 1 egg yolk, 1 tbsp low-fat quark and 2 tbsp cold water with a dough hook.
Finish kneading the dough by hand, shape it into a ball, wrap it in plastic wrap and chill it in the fridge for approx. 1 hour.
For the filling, clean 650 g currants and strip them from their stems.
Roll out the dough on a lightly floured work surface into a circle of approx. 30cm.
Line the bottom of a springform pan (approx. 24cm diameter) with parchment paper, lightly grease the side and dust it with flour.
Place the dough in the springform pan and press the edge of the dough firmly against the side. Prick it a few times with a fork (this keeps the dough from forming bubbles) and sprinkle with 1 tbsp breadcrumbs.
Preheat the oven to 180 °C (350 °F) conventional oven (top and bottom heat).
Beat 4 egg whites and 1 pinch salt until stiff. Slowly sprinkle in 90 g sugar and keep beating until the egg whites are very firm.
Mix 150 g ground almonds and 2 tbsp cornstarch with the currants and fold them into the beaten egg whites.
Spread the mixture over the dough in the springform pan and smooth the top.
Bake the cake on the middle rack for 45-50 min.
Take the currant cake out of the oven and let it cool completely in the pan.
To serve, dust with powdered sugar and enjoy.