Prune lekvar (a. K.a. Lackva) is basically prune butter. Here is a recipe to make your own from _The Complete Cookie_ by Barry Bluestein and Kevin Morrissey.

Combine 24 ounces pitted prunes and 2/3 cup water in a saucepan. Bring to a boil. Reduce the heat, cover, and simmer for 20 to 25 minutes, until fork tender.

Mash the prunes to a smooth consistency with a fork. Drop a teaspoonful onto a small plate. If a ring of water forms around the edge, return the prune butter to the pan and cook for about 3 minutes more over low heat, stirring constantly. Allow to cool completely before using.