1. Preheat oven to 375 degrees and line a baking pan with parchment paper.
2. Combine chicken, enchilada sauce, cilantro, lime juice, celery, tomatoes, pepper and salt in a large bowl.
3. Top bottom half of buns with chicken mixture then with shredded cheese before covering with top half of bun.
4. Lightly brush butter on tops of buns.
5. Place in oven until cheese is melted and top of bun is toasty (about 5-7 minutes).
6. Serve with Tortilla chips and salsa.