Mix the flour, sugar and vanilla sugar. Heat the milk in the microwave for about 30 seconds. (The optimum temperature for yeast fermentation is 32 ° C. Caution: baker`s yeast is inactivated from 45 ° C.)
Crumble the yeast into the milk, dissolve it and add to the flour-sugar mixture, mix and let rise for 5 minutes.
Melt the margarine, mix it with the milk, egg yolk and salt and add to the pre-dough. Knead the dough until smooth with your hand or a dough hook. If it`s too sticky to add a little more flour, it`s too dry to add a little milk.
Cover the bowl with a damp towel and place in a warm place for 30 minutes, e.g. on a low heater.
Knead the yeast dough again, shape into a roll and divide into 12 equal pieces. Shape the pieces into circles, put a teaspoon of jam on each and then shape them into balls. Put the balls in a well-greased tin not too close to each other and let rise for about 20 minutes.
Then the Buchteln are baked at 200 ° C for about 20-25 minutes.
Sauce:
Carefully mix the cream and mascarpone together until creamy. Beat the egg white and fold in carefully. Sweeten with vanilla sugar as desired.