Preheat the oven to 180°C/350°F. To make the cake base, whisk together sugar, vanilla sugar, egg yolks, and soft butter. Add flour, baking powder, and milk, and mix to combine. Fill the batter into a greased and flour-dusted springform pan. Bake at 180°C/350°F for approx. 15 min. Set aside.
To make the meringue, beat egg whites until foamy. Then add sugar and vanilla sugar and continue to beat until stiff peaks form. Gently fold the freshly plucked, washed, and destemmed red currants through half of the meringue. Now spread this mixture on top of the cake base, topped by the remaining meringue. Bake again at 180°C/350°F for approx. 15 min.
Set cake aside to cool, then transfer to the fridge.