First, just bring the yeast into a room temperature milk and stir it up and leave aside for a few minutes.
Add the powdered sugar and the salt to the flour and simply mix the dry ingredients together. Make sure all evenly mixed.
Add the butter in the mixed ingredients, and needs to be incorporate with each other. Mix it together. It will take for a few minutes.
Add the previously mixed liquid and the eggs, and start mixing the ingredients again. Continue mixing until the dough starts to come off from your hand and not sticking.
When the dough more comes together to a ball, dump it unto the work surface and continue mixing there.
When it's done, cut it into two pieces, shape them into a ball shape, pack them into a plastic wrap and rest them in the refrigerator for 1 hour.
Poppy Seed and Walnuts Filling Preparation
Put the sugar and the vanilla sugar in the fillings. Put the zest of the lemon also in the fillings. Now blend the ingredients in both mixing bowls.
Start ladling the boiling water into both fillings. Then mix them together. Put extra water if you need to.
The Rolling Preparation
After an hour, take the doughs out from the fridge and start to roll them. Try to roll them to a shape closest to a rectangle. Keep rolling them until the thickness is about 3 mm.
Then apply the fillings on the doughs. The Walnuts Filling in one dough the Poppy Seeds filling on the other one. Filling them almost all the way to the edges.
Then press the two sides down then roll them up. Not too tight and not too loose.
When you ready, transfer them onto a baking sheet.
Then, brush them with egg yolks then put them in the fridge for 30 minutes to dry, then repeat it again. Brush with egg yolks and put in the fridge for another 15 minutes.
Preheat the oven to a 200 Celsius - 400 Fahrenheit
When it's dry, this time brush them with egg whites only. Then with a thootpick or a skewer poke holes in the dough, on the top and on the side to let the moist escape. This time leave it in room temperature for 15 minutes more to rise.