Melt 50 g butter. Warm the milk lukewarm. Dissolve yeast in it. Put 75 g sugar, flour, salt and lemon zest in a bowl. Add the yeast milk, egg and liquid butter and work into a smooth dough with the dough hooks of the hand mixer.
Shape into a ball with floured hands and place in a bowl sprinkled with flour. Dust the yeast ball lightly with flour, cover and leave to rise in a warm place for about 20 minutes. In the meantime, wash, halve and stone the plums. Cut remaining butter into small cubes. Roll out the dough on a greased baking tray (32 x 38 cm). Let it rise again for another 15 minutes. Spread the plums on top, press them in slightly. Press small depressions into the dough between the plums. Put butter cubes in. Sprinkle with almond flakes and remaining sugar.
Let it rise again for another 15 minutes. Spread the plums on top, press them in slightly. Press small depressions into the dough between the plums. Put butter cubes in. Sprinkle with almond flakes and remaining sugar. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 20 -25 minutes. Results in approx. 24 pieces