Heat the oven to 180°C.
Whisk half the quark with the egg yolks, then add the baking powder, 3 tbsp sweetener and 1 tsp vanilla extract.
Whisk egg whites until they form soft peaks, then gently fold them into the yolk mixture.
Line a rectangular Swiss roll tray with baking paper and spray with plenty of Frylight. Carefully pour the mixture in the tray.
Bake for 10 minutes or until golden brown. Remove from the oven and allow to cool for 5 minutes. Peel off the baking paper from the cake and allow to cool fully.
Meanwhile, mix the remaining quark, sweetener and vanilla extract. Spread this cream on the biscuit and scatter some raspberries, saving a few for the top.
Gently roll up the cake into a roulade and top with the remaining raspberries and mint leaves to decorate.