Put 400 g flour, 60 g sugar, 1 vanillin sugar, 1 pinch of salt and 1 egg in a bowl. Crumble the yeast, stir with 1 tbsp. sugar in the cup until liquid
Melt butter and add milk. Pour the yeast into the flour mixture and knead everything smooth with the hand mixer. Cover and leave to rise in a warm place for about 40 minutes
Grease a fat pan (approx. 32 x 39 cm; approx. 3.5 cm deep) and dust with flour. Wash plums, remove stalks, cut lengthwise and stone them
Knead dough briefly. Dust with a little flour, roll out on the fat pan and press up the edge 2-3 cm. Cover the pan and let it rise for about 10 minutes. Place plums close together like roof tiles. Pre-bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 25 minutes
Separate 4 eggs. Beat 4 egg whites and 1 pinch of salt until stiff, adding 75 g sugar and 1 vanillin sugar. Fold in 4 egg yolks one by one. Sift 100 g flour and baking powder on top and fold in. Spread on the plums. Bake at the same temperature for about 10 minutes. Let it cool down. Dust with icing sugar