Add the shredded chicken, cream of chicken soup, sour cream, shredded cheese, salt, and pepper to a large mixing bowl and stir until fully combined.
Spread the chicken mixture into a greased 9x13-inch baking dish. Set aside.
Add the Ritz crackers, butter, and poppy seeds to a separate small mixing bowl and mix with your hands until the crackers are fully moistened with butter.
Sprinkle the cracker mixture evenly over the top of the chicken mixture.
Bake the casserole in the preheated oven for 30 minutes, or until the edges are hot and bubbling and the crackers are golden brown.
Store any leftovers covered in the refrigerator for up to three days.
Notes
Recipe Tips and Variations
Use leftover chicken: This is a good way to use up cooked chicken from another meal.
Try rotisserie chicken: It makes this recipe especially quick to prepare.
Change the cheese: Regular cheddar, sharp cheddar, or a cheddar blend will all work.
Don’t crush the crackers too finely: Leaving some texture gives the topping a better crunch.
Watch the topping near the end: If it’s browning faster than you’d like, loosely cover the casserole with foil.
How to Store
Store leftover poppy seed chicken casserole covered or in an airtight container in the refrigerator for up to 3 days.
Reheat individual portions in the microwave until hot, or cover the baking dish with foil and warm it in the oven.