Warm 50 ml of milk slightly. Dissolve 1 teaspoon sugar and yeast in it. Put the flour into a bowl, make a depression in the middle and pour in the yeast mixture. Mix with some flour and let it rise in a warm place covered for about 5 minutes.
Melt the fat, add the rest of the milk. Stir yeast dough lightly. Add the fat-milk mixture, 3 tablespoons of sugar, lemon zest and egg and mix everything with the dough hooks of the hand mixer to a smooth dough.
Cover and leave to rise in a warm place for another 30 minutes. In the meantime, wash the plums, drain, halve and stone them. Cut the plum halves in half. Grease a glass baking tin or a fat pan (32 x 38 cm).
Press the dough into the baking tin with floured hands. Cover with the plums in flakes. Sprinkle with 2-3 tablespoons of sugar. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 40 minutes.
Remove and let it cool down. Whipped cream tastes good with it.