Preheat the oven to 350°F.

Boil the chicken breast for 10 minutes or until fork tender, then use two forks to shred the chicken or slice it up and set it aside in a large bowl.

In the same large bowl, combine the onions, soup, and sour cream and mix until well combined.

Spray the baking dish with nonstick cooking spray and spread the mixture into the baking pan.

In a small bowl, combined crushed ritz crackers and melted butter and mix.

Sprinkle the cracker mixture over the casserole.

Bake for 25-35 minutes until the cracker topping is golden brown and the casserole is bubbly.

Serve and enjoy!