Step 1
Combine warm milk yeast and 1/2 cup of flour for dough in the bowl of a stand mixer and whisk to combine. Let sit until a \sponge\ forms about 30 minutes.
Step 2
Add egg yolks sugar melted butter salt and vanilla extract to the \sponge\ and whisk until combined. Add remaining 1 cup flour and mix using a dough hook attachment on low speed scraping down the bowl occasionally with a spatula until a soft smooth slightly elastic dough forms about 5 minutes. Add more flour and continue to knead if the dough seems too wet and sticky.
Step 3
Remove dough from the bowl and knead by hand checking consistency about 1 minute adding a little more flour if necessary.
Step 4
Transfer the dough to a lightly greased bowl. Toss to coat cover and let rise in a warm spot until doubled in size about 2 hours.
Step 5
While the dough is rising add butter milk honey sugar and water to a saucepan and place over medium-high heat; bring to a simmer. Add poppy seeds and cook stirring until the mixture thickens up to a spreadable texture about 5 minutes. Turn off the heat and allow to cool to room temperature before using 20 to 30 minutes.
Step 6
Preheat the oven to 375 degrees F (190 degrees C). Line a baking sheet with a silicone baking mat (such as Silpat®).
Step 7
Once the dough has risen transfer to a lightly floured surface and use your hands to roll into a log shape about 15 inches long. Switch to a rolling pin and roll the dough out into a 10x18-inch rectangle about 1/8-inch thick.
Step 8
Spread cooled filling over top leaving about 1 1/2 inches of dough exposed on the longer side that you'll be rolling towards. Brush the exposed edge of dough very lightly with water.
Step 9
Roll up the dough and filling toward the edge you just brushed finishing with the seam on the bottom. Seal the ends and use your hands to shape the roll as evenly as possible. If you have lots of excess dough on either end it can be trimmed off.
Step 9
Cut the roll into 8 even pieces and lay flat on the prepared baking sheet. If possible tuck any seams under the dough spiral as it's placed down. Let sit for 5 minutes.