In a small bowl combine the sugar and zest. Let sit.
FOR THE DOUGH
In the mixing bowl add the milk and honey and stir, sprinkle the yeast on top and let sit 5-10 minutes, mix. Add the sugar, vanilla, egg yolk, melted butter, flour and zest, start to knead then add the salt, and knead for 8 minutes, if the dough appears to dry then add some softened butter.
Move the dough to a lightly floured flat surface and gently knead to form a dough then place in a lightly oiled bowl, cover and let rise in a warm draft free area until doubled in bulk, 1-2 hours.
Roll the dough into a rectangle 1 cm thick 36x24cm long, spread the cream cheese or ricotta on the top, sprinkle with the sugar zest mixture. Roll up tightly lengthwise. Then cut the dough in half again lengthwise, twist it to form a braid. Place the braid in a greased and floured or sprayed 9 inch loaf pan. Cover and let rise 1-2 hours or until doubled.
Pre-heat the oven to 350F/180C.
Brush the risen braid with milk and bake approximately 25 minutes. Let cool on a wire rack. Drizzle with a lemon glaze if desired. Enjoy!
LEMON GLAZE
Combine one cup of powdered/icing sugar and 2-3 tablespoons lemon juice or a combination of lemon juice and cream until smooth and thick.
Notes
Store: If serving the same day, the babka can sit out for a few hours. After that, refrigerate it in an airtight container because of the ricotta or cream cheese filling. Bring to room temperature before serving.Freeze: Wrap the loaf tightly, without the glaze, and freeze for up to 2 months. Thaw, then glaze before serving.