In a large pot, combine chicken pieces, water, kosher salt, peppercorns, and chicken bouillon. Bring to a boil, then simmer for 1 hour until chicken is tender.
Remove chicken and let cool; reserve broth.
In a mixing bowl, combine flour, celery salt, onion powder, and black pepper. Gradually add reserved broth to form a soft dough.
Roll out dough on a floured surface to about 1/4-inch thickness.
Cut dough into squares and place cooked chicken pieces on each. Fold and seal the edges to form pastries.
Place pastries in a baking dish and pour some broth over them.
Bake at 375°F (190°C) for 25-30 minutes or until golden and flaky.
Serve warm with your favorite sides like coleslaw or garlic bread.