A common eastern European filling for cookies and pastries is Prune Butter.  An example is Grandma’s Rolled Crescents which is a cookie from Ukraine.  I was able to find Prune Butter for sale on line, but californiaprunes.org had a recipe online which is very easy to make.

½ lb. prunes

¾ cup water

¼ tsp. kosher salt (I used Morton’s)

½ tsp. vanilla extract

1-3 Tbs. brown sugar (depends on desired sweetness.  I used 2 Tbs.)

Bring the prunes and water to boil in a small saucepan.  Reduce to a simmer and cook covered until the prunes are meltingly soft, about 15 minutes.

Remove from the heat and add the remaining ingredients.  Mash into a smooth paste.  (I used a pastry cutter.  The original suggested a food processor or blender which would have involved a lot of clean up afterwards.)

Start with 1 Tbs. of brown sugar and add more (if necessary) for the desired level of sweetness.