In a large bowl, beat the cream cheese, milk, dill, salt and pepper until blended. Stir in the chicken, celery and onions.
Unroll crescent roll dough and separate into 12 rectangles, four from each tube; place on a greased baking sheet and press the perforations together. Spoon 1/2 cup of chicken mixture into the center of each rectangle. Bring edges up to the center and pinch to seal. Brush with butter; sprinkle with bread crumbs.
Bake at 350° for 15-20 minutes or until golden brown.