Creating the Best Ever Chicken and Rice Casserole is straightforward if you follow these detailed steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Prepare Chicken: Cook the chicken breasts either by boiling or baking. If baking, season with salt, pepper, and paprika for added flavor. Once fully cooked, shred the chicken.
3. Cook Rice: If you haven’t done so yet, prepare the rice according to package directions.
4. Mix Ingredients: In a large mixing bowl, combine the shredded chicken, cooked rice, cream of chicken soup, cream of mushroom soup, chicken broth, milk, diced onion, frozen mixed vegetables, garlic powder, onion powder, black pepper, and thyme. Stir until well combined.
5. Transfer to Casserole Dish: Pour the chicken and rice mixture into a greased 9×13 inch casserole dish. Spread it out evenly.
6. Add Cheese: Sprinkle shredded cheddar cheese on top of the mixture.
7. Prepare Topping: In a small bowl, mix together the breadcrumbs and melted butter. Stir until all breadcrumbs are coated.
8. Sprinkle Topping: Evenly distribute the breadcrumb mixture over the cheese layer.
9. Bake: Place the casserole in the preheated oven and bake uncovered for 45-50 minutes, or until the top is golden and bubbly.
10. Cool and Serve: After baking, let it cool for about 10 minutes before serving to allow the flavors to meld.

With these steps, you can create the Best Ever Chicken and Rice Casserole that is sure to become a regular on your menu.