Mix flour and baking powder in a bowl. Add 250 g sugar, salt, 2 eggs and fat in pieces. Knead first with the dough hooks of the hand mixer, then with your hands to a smooth dough.
Cover and put in a cool place for about 30 minutes. In the meantime grease a fat pan (approx. 34x38 cm) well. Separate 6 eggs and put the egg whites in a cool place. Beat the egg yolks, remaining eggs and 250 g sugar until frothy.
Stir in yoghurt, quark, pudding powder, grated lemon peel and oil. Roll out the dough evenly on the bottom of the fat pan and prick several times with a fork. Pour in the yoghurt mixture, smooth it down and bake in the preheated oven (electric cooker: 175 °C/ gas: level 2) for approx. 45 minutes.
Shortly before the end of the baking time, beat the remaining egg whites until stiff and finally add the remaining sugar (80 g). Spread the beaten egg whites on the hot cake and bake at (electric oven: 200 °C/ gas: level 3) for about 10 minutes.
Let the cake cool completely on the fat pan. In the meantime wash the strawberries, drain well and cut into quarters. Whip the cream and vanilla sugar until stiff and place in a piping bag with star-shaped spout.
Cut the cake into about 24 slices and dust with icing sugar. Decorate with cream tuffs and strawberries and sprinkle with pistachios.