Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine your shredded chicken, softened cream cheese, sour cream, cheddar cheese, and onion. Mix until smooth.

Grease a 9x13-inch casserole dish and spread the filling evenly.

Crush the Ritz crackers and sprinkle them over the top of the chicken mixture.

Bake for approximately 30 minutes or until golden brown and bubbly.

Let it sit for 5-10 minutes before serving.