A good recipe for povitica is 1 1/4-ounce package active dry yeast, 1 tablespoon of sugar and 6 tablespoons of milk. Combine these ingredients in the bowl of a stand mixer with additional milk and sugar, salt and melted unsalted butter and 1 egg. Gradually beat in 2 1/2 cups flour. Beat the dough, and proof. Make a puree of walnuts, butter, milk, cinnamon and egg whites. Spread the puree over the rolled dough. Proof and bake for 1 hour.
Allow the yeast and milk mixture to sit in the mixing bowl for 10 minutes or until it is foamy. Add 6 more tablespoons of milk, 1/2 cup minus 1 tablespoon of sugar, 1/2 tablespoon of kosher salt, 4 tablespoons of melted unsalted butter and 1 egg. Turn the machine on, and gradually add 2 1/2 cups of flour. Once the dough becomes smooth, remove it, and cover it with plastic wrap. Allow it to sit for 1 hour or until it doubles in size.
For the filling, puree 1/2 cup of toasted walnut halves, 1/2 cup of sugar, 4 tablespoons of unsalted butter, 2 tablespoons of milk and 1 teaspoon of ground cinnamon in a food processor. Beat 2 egg whites in a separate bowl until stiff peaks form. Fold the walnut paste into the egg whites.
Roll the proofed dough into a 10 by 4-inch long oval with 1/16-inch thickness. Cover the walnut filling with the dough, and roll the dough tightly, starting at the narrow end. Place it into a loaf pan, and proof for another hour. Bake the bread at 350 degrees Fahrenheit for one hour, and then let it cool.