Shred the chicken

• Pull the meat off the rotisserie chickens and shred it into a large bowl.

Make the cracker topping

• Crush the Ritz crackers.
• Melt the butter and pour it over the crushed crackers.
• Mix well until the crumbs are evenly coated.

Mix the filling

• Add the cream of chicken soup to the shredded chicken.
• Stir in the sour cream until combined.
• Add the poppy seeds if using, and mix well.

Layer the casserole

• Spread half of the cracker crumbs in the bottom of the baking dish.
• Spoon the chicken filling over the crumbs and spread evenly.
• Scatter the remaining crumbs over the top.

Bake covered

• Preheat the oven to 190 °C (375 °F).
• Cover the dish and bake.

Bake uncovered until golden

• Uncover the dish and return it to the oven until nicely browned.

Rest and serve

• Let the casserole stand after removing it from the oven before serving.