Chocolate-Swirled Babkas

I found this in 'Cooking From A-Z', given to me as a gift. This is a sweet bread (obviously!) and tastes wonderful with coffee or tea. Prep time includes rising time.

• Ready In: 3 hrs 20 mins
• Yields: 2 loaves

Ingredients

• 2  packages active dry yeast
• 1⁄2 cup warm water
• 1⁄3 cup sugar
• 2⁄3 cup  warm milk
• 1⁄2 teaspoon salt
• 1⁄2 teaspoon vanilla
• 3  tablespoons butter, softened,plus
• 3  tablespoons butter, melted
• 4 1⁄2-5  cups flour
• 3  eggs
•  oil, for greasing
• 1  cup  coarsely chopped walnuts

• Cocoa Filling

• 1⁄3 cup  unsweetened cocoa
• 2⁄3 cup sugar

• Streusel Topping

• 2  tablespoons butter, softened
• 1⁄4 teaspoon cinnamon
• 1⁄3 cup confectioners' sugar
• 1⁄4 cup flour

Directions

1. In the bowl of an electric mixer, sprinkle yeast over the water; add 1 teaspoon sugar, let stand until yeast is soft, about 5 minutes.
2. Mix in remaining sugar, milk, salt, vanilla and softened butter.
3. Add 2 1/2 cups flour, mix to blend then beat, at medium speed, until smooth and elastic, about 5 minutes.
4. Separate one of the eggs; reserve white for glaze; beat in egg yolk and remaining whole eggs, one at a time; stir in about 1 1/2 cups more flour to make a soft dough.
5. Turn dough onto a board coated with some of the remaining 1/2 to 1 cup flour; knead until dough is smooth and satiny and small bubbles form just under the surface, 10-12 minutes, adding just enough flour to prevent dough from being too sticky.
6. Turn dough into a greased bowl; cover with plastic wrap and a towel; let rise in a warm place until doubled in bulk, about 45 minutes to 1 hour.
7. Place dough on a floured surface and punch down; cover with inverted bowl and let rest for 10 minutes.
8. Divide dough in half; roll each half on a floured surface to a 10 x 20-inch rectangle; brush 1 1/2 tablespoons of the melted butter over each rectangle, leaving about a 1/2-inch margin on all edges.
9. Sprinkle half of the Cocoa Filling* over buttered surface of each rectangle, then sprinkle each rectangle with 1/2 cup walnuts.
10. Starting with a 20-inch side, roll each rectangle of dough tightly, jelly-roll style; pinch edge to seal.
11. Zigzag each roll back and forth to fit into a well greased 5x9-inch loaf pan.
12. Let rise until almost doubled in bulk, 35-45 minutes.
13. Preheat oven to 350°.
14. Beat reserved egg white with 1 teaspoon water; brush egg white mixture over loaves; sprinkle each loaf with half of the Streusel Topping**.
15. Bake until babkas are well-browned, 30-35 minutes then carefully remove loaves from pans and let cool on wire racks.
16. *CocoaFilling: in a small bowl mix cocoa and sugar until well combined and no lumps remain.
17. **StreuselTopping: In a medium bowl beat butter with cinnamon until fluffy; gradually beat in sugar, then mix in flour until crumbly and uniformly combined.