• Pour lukewarm milk into a large mixing bowl and dissolve fresh yeast in it. Add 80 g of flour from the total amount mentioned in the ingredient list and stir thoroughly. Cover the pre-dough with a towel and let it rise in a warm place for 30 minutes.
• Mix sour cream, eggs, egg whites, sugar, orange zest and salt until homogeneous.
• Add the sour cream-egg-sugar mixture to the pre-dough and mix until homogeneous.
• Add cognac and in portions, gradually add the remaining flour and knead to form a soft, somewhat sticky dough. Cover the dough in the mixing bowl with a towel and let it rise in a warm place for 20 minutes. (For this, follow my tips and tricks here at the top of the post to make your yeast dough perfect).
• Knead softened butter into the dough in batches until it has completely absorbed the butter and regained a homogeneous consistency. Then knead the yeast dough for about 10 minutes so that it becomes elastic, cover it with a towel in the mixing bowl and let it rise in a warm place for 50 minutes.
• Knead the dough briefly and let it rise again in a warm place for another 30 minutes.
• Divide the dough into two pieces (One loaf pan was slightly larger than the other in my case. Accordingly, I had divided the dough into a slightly larger and a slightly smaller piece.) and shape each piece into a ball. Spread the balls on the work surface, cover them with a towel or plastic wrap, and let them rest for 10 minutes.
• Roll each dough ball into a square about 0.3 cm thick.

Filling the dough

• Brush both squares evenly with softened butter.
• Sprinkle one of the two squares evenly with ground poppy seeds and the other square with ground walnuts.
• Roll up the square with walnut and with poppy seeds into one roll each. First, cut one of the two rolls in half lengthwise with a sharp knife, leaving one end of the roll about 1 - 2 cm uncut. Now turn the two parts of the roll with the cut facing up, braid them into a plait and place the plait in a loaf pan greased with vegetable oil. Repeat the same with the second roll and place the braid in the second loaf pan.
• Cover both yeast braids in the baking dishes with towel and let them rise in a warm place for 40 minutes.
• Mix egg yolk with 1 tablespoon of water, brush the top of the yeast plaits with it and let them rest for about 5 minutes (In this time you can preheat the oven).
• Bake the yeast plaits with nut and poppy seed filling in a preheated oven at 170 °C top and bottom heat for about 30 minutes. In the last 15 minutes or so, move them to the second rack from the bottom, when their surface is already brown, so that they don't burn.

Preparation of the sugar syrup

• Pour boiling water into a small mixing bowl and dissolve sugar and vanilla sugar in it.
• Coat the yeast braids in the baking pans with the sugar syrup immediately after you take them out of the oven, while they are still hot. Take the plaits out of the baking pans and let them cool down a bit.