In a small bowl, add the yeast and water and mix together to make a paste. Set aside.
In a large mixing bowl, cream the butter and sugar together. Add salt, egg yolks, sour cream, and start adding the flour 1 cup at a time until combined.
Add the proofed yeast (should be bubbly) to the flour mixture and combine. Dough will be sticky. Refrigerate 1 hour or overnight (see note*).
Remove dough from fridge and separate into 3-4 balls.
Roll out each ball into rectangles (about 1/4 of an inch works well), adding more flour as needed to prevent sticking.
Mix together all ingredients for nut filling and spread evenly over dough, leaving a little room near the edges so it doesn't overflow when rolled. Roll tightly.
Preheat oven to 350°F. Let potica rise for 1 hour (will rise more in the oven if the dough has been refrigerated for a longer time).
Bake at 350°F for 30 minutes or until browned.
I tried this recipe by refrigerating the dough only briefly (30 minutes to an hour) and also overnight. If you are in a hurry, it will still turn out mostly the same by refrigerating briefly but the longer time will help the dough be more manageable when you need to roll it out from my experience.