Mix flour and salt in a bowl, make a depression in the middle and crumble the yeast into it. Heat 1/8 litre of milk and add to the yeast together with 1 tablespoon of sugar. Mix with some flour from the edge and let it rise covered in a warm place for about 20 minutes. Heat 1/8 litre milk. Add milk, 2 tablespoons of sugar, butter, 1 egg and lemon zest to the yeast dough. Knead with the dough hooks of the hand mixer for 3-4 minutes to a smooth dough. Cover and leave to rise in a warm place for 45-60 minutes.
Grease a fat pan (approx. 38 x 32 cm) and dust with flour. Knead the dough again briefly and roll out into a rectangle (slightly larger than the fat pan) on a floured work surface. Line the fat pan with the dough and press it up at the edge. Cover the pan and put to one side. For the filling, separate 4 eggs, chill the egg whites. Bring 1 litre of milk, vanillin sugar and 75 g sugar to the boil. Stir in semolina and let it swell for 5-10 minutes at low heat. Stir from time to time. Bring 3/8 litres of milk to the boil in a second pot. Stir the pudding powder, 75 g sugar and 1/8 litre milk. Remove the milk from the stove, stir in the custard powder and place back on the stove. Cook for at least 1 minute while stirring. Stir the pudding into the semolina.
Stir from time to time. Bring 3/8 litres of milk to the boil in a second pot. Stir the pudding powder, 75 g sugar and 1/8 litre milk. Remove the milk from the stove, stir in the custard powder and place back on the stove. Cook for at least 1 minute while stirring. Stir the pudding into the semolina. Remove from heat and add the egg yolks while stirring. Beat the egg whites until stiff and finally add 25 g sugar. Fold the beaten egg whites into the hot pudding mixture and spread on the yeast dough. Separate 2 eggs and beat the egg whites until stiff. Mix egg yolk and sour cream, fold in the beaten egg white and spread the mixture as a thin layer on the pudding. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35 - 40 minutes. Allow the finished Schmantkuchen to cool in the fat pan, cut into pieces and dust with icing sugar
Remove from heat and add the egg yolks while stirring. Beat the egg whites until stiff and finally add 25 g sugar. Fold the beaten egg whites into the hot pudding mixture and spread on the yeast dough. Separate 2 eggs and beat the egg whites until stiff. Mix egg yolk and sour cream, fold in the beaten egg white and spread the mixture as a thin layer on the pudding. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35 - 40 minutes. Allow the finished Schmantkuchen to cool in the fat pan, cut into pieces and dust with icing sugar