Cut rolls and peeled rhubarb into slices. Pour hot whipped cream over the buns to soften them and mix with a spoon. Mix sugar, egg yolks, vanilla sugar and cinnamon until creamy, mix well with rhubarb slices and softened bread. Finally, gently fold in the stiffly beaten egg whites.
Butter a baking dish well, pour in the mixture and top with butter flakes. Bake in a heated oven at 200 °C for about
45 minutes.
Serve with whipped cream whipped with powdered sugar.