Raspberries and blueberries selected. Wash and drain the blueberries and strawberries. Wash and quarter the strawberries. Mix the berries with 50 g sugar and lemon peel and place in an ovenproof dish
Separate eggs. Whip egg whites first, then cream until stiff. Whip egg yolks, cardamom and 75 g sugar until light creamy. First fold approx. 1/4 of the egg whites into the egg yolks, then fold in the remaining egg whites and cream. Spread the egg mixture over the berries. Bake in the preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 20-30 minutes until brown
Remove the gratin, dust with icing sugar and serve with whipped cream