As an alternative to this recipe, you may use Sour Cherry Preserves as a filling.
Combine in a medium saucepan:
Bring to a boil and cook until the juices have reduced and are no longer runny, about 15 minutes. Combine in a small bowl:
Stir the cornstarch slurry into the cherries. Boil to thicken, about 1 minute. Remove from the heat and let cool.