Step 1
Combine warm milk yeast and 1 teaspoon sugar in a large bowl; stir well. Let stand until yeast softens and begins to form a bubbly foam about 5 minutes.
Step 2
Stir 1/2 cup sugar and lemon zest into the yeast mixture. Whisk in 2 eggs and egg yolks 1 at time mixing well after each addition. Add salt. Stir in flour gradually. Add melted butter and blend well. Knead dough until glossy and elastic about 10 minutes. Form into a ball and place in a large lightly-oiled bowl and turn to coat. Cover with a clean towel and let rise in a warm place until doubled in volume about 1 hour.
Step 3
Place poppy seeds in a small pot and cover with 1 cup milk or more as needed. Bring to a simmer over medium heat. Remove from heat and let sit 15 to 20 minutes. Drain milk. Pulse poppy seeds in a food processor or leave them as is. Add raisins egg whites honey 1/4 cup sugar walnuts and 3 1/2 tablespoons butter to poppy seeds and stir to combine for the filling.
Step 4
Punch down dough turn out onto a lightly floured surface and knead briefly. Divide dough in half and roll one portion into a 10-inch sheet. Cover with 1/2 the filling leaving a 1/4- to 1/2-inch edge. Roll up into a log. Repeat with the second half.
Step 5
Arrange both rolls onto a greased baking sheet. Cover with a kitchen towel and let rise until doubled in volume about 30 minutes more.
Step 6
Preheat oven to 350 degrees F (175 degrees C).
Step 7
Whisk remaining egg with 1 tablespoon water; brush mixture over tops of rolls.
Step 8
Bake rolls in the preheated oven until golden 20 to 25 minutes.