1. Preheat the oven to 390°F (200°C). Grease a 9 inches (23cm) springform tin or baking tin with loose bottom and line with parchment paper. Set aside. Add the cookies to a freezer bag and crush until you get fine crumbs. Set aside. Wash the gooseberries, remove the stems and let drain.

2. For the streusel add the flours, xylitol (or sugar), and butter to a large bowl an rub between your fingers to form streusel. Take about 2/3 of the streusel and fill into the prepared baking tin. Press to the bottom to get one even layer. Sprinkle about 2/3 of the crushed cookies on top and lightly press down. Mix the remaining streusel, crushed cookies, and the sliced almonds and set aside in the fridge until needed. Bake the cake base for about 10 minutes. Take out of the oven and reduce the heat to 350°F (180°C).

3. While the cake base is cooling down a bit, add the milk to a saucepan. Take some of that milk and mix in a separate bowl with the vanilla extract, cornstarch, and xylitol (or sugar) until smooth. Bring the milk in the saucepan to a boil, add the cornstarch mix and stir until the mixture thickens. Remove from the heat and let cool down for several minutes. Divide the eggs, whisk the egg whites with a pinch of salt until stiff peaks form. Set aside. Add the egg yolks to the pudding in the saucepan and mix until well combined. Add the curd (quark) and mix in well. Add the stiff egg whites and fold in carefully – you want to keep as much volume as possible. Pour the mixture onto the pre-baked cake base and smooth out the top. Bake for about 10 minutes, take out and place the gooseberries on top, sprinkle with the streusel mixture and place it back in the oven and bake another 30-35 minutes until the streusel have a nice golden color and the filling has set. Turn off the oven, open the door a bit and leave the cake in there for another 10-15 minutes, then take it out and let cool down completely on a wire rack. Place in the fridge for at least 1 hour after that.