1. In a large bowl mix flour, sugar, cocoa, and salt. Add the butter in small pieces and cut into pea-sized pieces with a pastry cutter* or a knife. Add the egg and mix everything, then knead to get a smooth dough. Try not to knead for too long, so the butter doesn’t get unnecessarily warm. Wrap the dough in plastic wrap, place it in the fridge, and let it rest for about 30 minutes.

2. While the dough is sitting in the fridge you can already prepare the filling by mixing the curd cheese (quark) with sour cream, sugar, cornstarch, vanilla extract, and salt in a bowl. Add the eggs and mix everything until well combined (working with a whisk only is fine here). Cover and set aside until needed.

3. Preheat the oven to 350°F (180°C). Lightly grease a loaf pan* (approx. 9×5.5 inches) and line with a piece of baking parchment. Roll out about 3/4 of the dough on a floured surface (preferably rectangular), then place that dough inside the pan and press down on the bottom and the sides. Cut off overlapping dough and press scraps to the bottom and side, wherever needed, to get an evenly thick dough layer all around. Roll out the remaining dough (not too thin) and cut out hearts in different sizes. Set aside.

4. Add a small amount of the filling to the pan and spread. Sprinkle the frozen raspberries on top and cover with the remaining filling. Smooth out the top and decorate with the dough hearts. Bake for about 55-60 minutes. The filling should have set but can still jiggle slightly in the center if you move the pan. Take out of the oven and let cool down on a wire rack. Lift the completely cooled cake out of the pan with the help of the baking parchment, place on a serving plate, and serve.