Warm up the milk. Crumble yeast into it, stir. Pour the flour into a bowl and make a depression in the middle. Sprinkle 50 g sugar on the flour rim. Pour yeast milk into the hollow, dust with some flour.
Cover and leave to rise in a warm place for about 15 minutes. Melt the fat. Add fat, 1 packet of vanilla sugar, 1 pinch of salt and 1 egg to the pre-dough. Work into a smooth dough with the dough hooks of the hand mixer.
Cover and leave to rise again for about 40 minutes. Grease a springform pan (24 cm Ø). Put the dough into the form, press it smooth, press the rim up about 1 cm. Sprinkle the dough base with breadcrumbs. Place the apricots on the dough with the convex side up.
Separate 3 eggs. Mix the egg yolks, 50 g sugar and 1 packet of vanillin sugar until creamy. Mix sour cream and starch and stir into the mixture. Spread the glaze over the apricots. Bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) on the middle shelf for about 35 minutes.
In the meantime, beat the egg whites until stiff, adding 150 g sugar. Take the cake out of the oven and spread the beaten egg white on top. Bake the cake at the same temperature for another 10 minutes.