Grease four small souffle pans with butter and sprinkle with sugar. Chill the pans in the freezer.
Beat the quark, egg yolks, vanilla and lemon zest. Beat the egg whites with the sugar until stiff. Fold in the starch. Gently fold the egg whites into the egg yolk mixture. Pour the cream into prepared pans. Preheat the oven to 200°C (approximately 400°F). Bake for 20 minutes. Dust with powdered sugar. Serve garnished with raspberries and mint.