Creating the Creamy Chicken and Spinach Casserole is simple and straightforward. Follow these steps for a successful dish:

1. Preheat the Oven: Begin by preheating your oven to 350°F (175°C).
2. Prepare Ingredients: If not already done, cook the chicken, rice, or pasta as necessary.
3. Mix the Base: In a large mixing bowl, combine the cream of chicken soup, sour cream, garlic powder, onion powder, salt, and pepper. Stir until well blended.
4. Add Chicken and Spinach: Fold in the shredded chicken and chopped spinach, ensuring everything is evenly coated in the creamy mixture.
5. Incorporate Cheese: Add the shredded cheddar cheese and grated Parmesan cheese to the mixture. Stir until fully combined.
6. Combine with Rice/Pasta: If using, fold in the cooked rice or pasta, mixing well.
7. Transfer to Casserole Dish: Pour the mixture into a greased 9×13-inch casserole dish, spreading it evenly.
8. Add Topping: If desired, sprinkle breadcrumbs over the top for added texture.
9. Bake: Place the casserole in the preheated oven and bake for 30-35 minutes, or until bubbly and golden on top.
10. Cool and Serve: Once out of the oven, allow it to cool for a few minutes before serving.

These simple steps will guide you in creating a delicious Creamy Chicken and Spinach Casserole that your family will love.