Wash the orange and rub the peel thinly. Mix flour, dry yeast, 100 g sugar, vanillin sugar, 1 pinch of salt and grated orange peel in a bowl. Melt butter in a saucepan. Add milk and warm up lukewarm. Pour butter-milk and egg to the flour-mix and knead with the dough hooks of the hand mixer to a smooth dough.
Cover and leave to rise in a warm place for about 45 minutes. Wash the plums, halve, stone and cut into thin slices. Knead the dough briefly and roll out rectangularly (approx. 30 x 35 cm) on a floured work surface. First crumble Amarettini on the dough, then spread the plums on top. Roll the dough up tightly from the narrow side and cut into approx. 11 slices. Place the dough snails close together in a greased springform pan (26 cm Ø), cover and leave to rise for about 15 minutes. Mix 1 tablespoon sugar and cinnamon. Sprinkle the cake with sugar-cinnamon and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes. Let the cake cool down in the tin on a cake rack.
Roll the dough up tightly from the narrow side and cut into approx. 11 slices. Place the dough snails close together in a greased springform pan (26 cm Ø), cover and leave to rise for about 15 minutes. Mix 1 tablespoon sugar and cinnamon. Sprinkle the cake with sugar-cinnamon and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes. Let the cake cool down in the tin on a cake rack. Dust with icing sugar before serving
waiting time approx. 1 1/4 hours