Dissolve yeast in 200ml of lukewarm water.
Sieve flour, sugar, and salt into a bowl and rub in butter.
Add eggs, yeast mixture, and remaining water to form a soft dough.
Cover and rest the dough for 10 minutes.
Knead on a floured surface for 5-10 minutes until springy.
Place in an oiled bowl and let rise until doubled in size.
Knead for 2-3 minutes then rest for 5 minutes.
Grind poppy seeds in a grinder.
Cook milk, sugar, zest, seeds, and raisins for 15 minutes.
Stir in lemon juice, brandy, liqueur, and butter for 2 minutes.
Stir in vanilla and spread on a tray to cool.
Grease and sugar a 33 x 25cm deep tin.
Preheat oven to 200°C.
Roll dough to 26 x 40cm, brush with butter, and spread filling.
Roll up dough and seal the edge with water.
Brush the log with melted butter.
Trim the ends and slice the log into 12 portions.
Place buns cut-side down in the tin with small gaps.
Brush with egg wash and prove for 30 minutes.
Bake on the middle shelf for 18-20 minutes.
Boil bun wash ingredients for 3-4 minutes to create syrup.
Brush hot buns immediately with the syrup.
Cool for five minutes, separate, and serve warm.