Method
- Combine the yeast and warm milk, and let it sit until foamy. In a large bowl, mix together the flour, sugar, and salt. Add the egg yolks, sour cream, vanilla extract, walnut oil, and butter. Knead the dough until smooth and elastic. Cover and let rise until doubled in size.
- Prepare the filling: Whip the egg whites with sugar until soft peaks form. Fold in the ground walnuts, cocoa powder, vanilla extract, rum extract, orange extract (if using), and walnut oil.
- Roll out the dough, spread the filling evenly, then roll and twist into a loaf shape. Let it rise again until puffy.
- Preheat the oven to 350°F. Brush the loaf with egg wash and bake for approximately 50 minutes, or until golden brown and cooked through.
- Allow to cool before slicing and serving.