Dissolve fresh yeast and sugar in lukewarm milk.
Add egg, egg white and salt and mix until homogeneous.
Add flour in portions and knead into a soft dough.
Knead soft butter into the dough and then knead the dough for about 10 minutes.
Let the dough rise, covered, in the mixing bowl in a warm place for 1 hour.
Fold the baking paper into an envelope about 15 cm x 15 cm, put 150 g of cold butter cut into thin slabs into it and roll it out with a rolling pin so that it is evenly distributed in the envelope. Put the butter plate in the envelope in the refrigerator while the dough is rising.
Roll out the dough on the floured work surface into a rectangle about 16 cm x 31 cm (i.e., slightly larger than twice the size of the butter plate).
Get the butter plate out of the refrigerator and out of the baking paper envelope and place it on one side of the rolled out dough rectangle, leaving a border about 1 cm wide. Cover the butter plate with the second half of the dough and press the edge of the dough down on all sides.
Roll out the buttered dough into a long rectangle, fold one of the shorter sides of the rectangle in half on the center, and place the second short side over it. Wrap the dough plate in baking paper or plastic wrap and refrigerate for 1 hour.
Roll out the dough plate again on the floured work surface into a long rectangle, fold one of the shorter sides of the square in half on the center again and place the second short side over it. Wrap the dough plate again in baking paper or plastic wrap and refrigerate for 1 more hour.
Line the baking springform pan with parchment paper.
Roll out the dough on the floured work surface to a long rectangle about 0.5 cm thick and cut it from the shorter side into strips about 5 cm wide (7 strips for me).
Cut each strip lengthwise down the center about 1 cm from the edge from one of the sides into two strands, braid each strand into a braid, and glue the ends of each braid together.
Spread the braid rolls, ends down, in the baking springform pan and let them rise at room temperature for 20 minutes.
Mix egg yolk with 1 tablespoon of milk and carefully brush the rolls with it.
Bake the rolls in a preheated oven at 200 °C top and bottom heat for about 20 minutes and let them cool down.