Step 1

Combine all of the ingredients in a saucepan except for the brown sugar. Stir and bring to a boil for one minute.

Step 2

Reduce heat to medium low so the mixture simmers slowly and constantly. Cover the pot. Let the mixture simmer covered for 20 minutes, stirring every few minutes.Remove the lid from the pan. Let the prunes continue to simmer for 3-5 more minutes, stirring frequently, until most of the liquid has evaporated/absorbed. Keep a close eye on the pan to make sure the prunes don't burn. When there are about 3 tbsp of liquid left in the pan, remove from heat.

Step 3

Stir the brown sugar into the prune mixture till brown sugar melts and dissolves.

Step 4

Mash the prune mixture with a potato masher till a smooth puree forms. Run a fork through the mixture to break up any pieces the potato masher missed. You can also use an immersion blender for a smoother puree, if you want to.

Step 5

Let cool to room temperature before using. Store in a sealed, airtight container in the refrigerator. Refrigerating the filling to chill completely will make it easier to work with when filling hamantaschen.