1-First Step: Mise en Place Start by prepping all components. Dice 1 lb cooked chicken into bite-sized pieces. Chop 1 medium onion and mince 2 garlic cloves. If using fresh spinach, rinse 10 oz; thaw and drain frozen. Shred 2 cups cheese and measure 2 cups cooked rice. Grease a 9×13-inch baking dish with cooking spray. This setup takes 10 minutes and prevents mid-cook rushes.

2-Second Step: Cook the Chicken and Aromatics In a large skillet over medium heat, sauté the chopped onion in 1 tbsp oil for 3-4 minutes until soft. Add minced garlic and cook 1 minute until fragrant. Stir in diced chicken to warm through, about 2 minutes. This builds a flavorful base. If starting with raw chicken, brown it first for 5-7 minutes until cooked to 165°F internal temperature.

3-Third Step: Wilt the Spinach Add 10 oz spinach to the skillet. Cook 2-3 minutes, stirring until wilted and most liquid evaporates. Season with salt, pepper, and 1 tsp Italian seasoning. Excess moisture can make the casserole watery, so press spinach gently with a spoon to drain. This step infuses greens with savory notes.

4-Fourth Step: Combine the Filling Remove skillet from heat. Mix in 2 cups cooked rice, 1 can cream of mushroom soup, 1 cup sour cream, and 1 cup shredded cheese. Stir until creamy and uniform. Taste and adjust salt or pepper. Pro tip: Use rotisserie chicken to cut prep time in half. Transfer this mixture to the prepared baking dish, spreading evenly.

5-Fifth Step: Add Toppings Sprinkle remaining 1 cup shredded cheese over the top, followed by 1/2 cup breadcrumbs. For extra crunch, mix breadcrumbs with 1 tbsp melted butter before sprinkling. This creates a golden crust that everyone loves.

6-Final Step: Bake and Serve Bake uncovered at 375°F for 25-30 minutes until bubbly, cheese melted, and top golden. Let rest 10 minutes to set. Serve hot with a side salad. Total time: 45-60 minutes. Cool leftovers promptly for storage. This easy chicken casserole shines with fresh ingredients and careful timing.