1. Preheat oven to 375°F. Line a cookie sheet with parchment paper.
2. Mix together all filling ingredients.
3. Warm milk or soy milk gently to about 95°F.
4. Dissolve yeast in milk.
5. Mix flour, butter and sugar until crumbly.
6. Add half of egg yolk, yeast mixture, and salt.
7. Knead the mixture well and divide into two portions. This process can be done in a food processor or by hand.
8. Roll each portion into a thin sheet, approximately 8x10inches.
9. Spread half the filling on each piece of dough. 10. Roll up tightly along the shorter edge, carefully transfer to the lined cookie sheet, seam down, and press the ends to keep the filling from coming out. 11. Beat the remaining half egg yolk with a few drops of water.
12. Brush the rolls with the egg yolk, and let them rise in a warm place for about an hour.
13. Place the cookie sheet in the refrigerator for an additional hour.
14. Brush the rolls with the egg white (beaten just a bit).
15. Prick the rolls with a fork in 3 or 4 spots.
16. Bake in the preheated oven for 30-40 minutes until golden.
17. Let cool before serving.