Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with aluminum foil; grease with cooking spray.
Melt butter in a large skillet over medium heat. Add onion and celery; cook and stir until softened, about 5 minutes. Stir in salt, poultry seasoning, and pepper; cook and stir until fragrant, about 1 minute.
Whisk eggs and chicken broth together in a large bowl. Fold in bread cubes and parsley. Pour in onion mixture; mix together until combined.
Shape mixture into 2-inch balls and arrange on prepared baking sheet.