Preheat oven to 350 degrees.
In a large soup pot, cover chicken breasts with enough cold water to cover over the top by an inch.
Add 2 teaspoons salt and 1 teaspoon black pepper.
Bring chicken to a boil over high heat and then reduce heat to medium-low and cover the pot, and allow the chicken to cook for about 30 minutes.
When cooking time is complete, the chicken should be tender. Remove chicken to a plate and allow it to cool to room temperature.
When chicken is cool enough to handle, remove the skin and bones and discard.
Dice the remaining chicken breast into bite-sized pieces and place into a large mixing bowl.
Add the remaining ingredients (except the crackers and butter) and mix to combine.
Grease a large baking dish and pour in the chicken mixture, smoothing out evenly. In a large Ziploc bag, crush crackers into pea sized crumbs and pour melted butter over. Seal bag and shake to make sure everything gets coated. Pour cracker mixture over casserole and spread evenly with hands.
Bake at 350 degrees for 30-45 minutes or until hot and bubbly and golden brown on top.