Prepare the Oven and Baking Dish: Preheat your oven to 375°F. Lightly grease a 9×13-inch baking dish. There is always something comforting about preparing a casserole dish for the oven. It signals that a warm homemade dinner is on the way.

Sauté the Onion and Garlic: Heat olive oil in a large skillet over medium heat. Add diced onion and cook for 4–5 minutes until softened. Stir in the garlic and cook for another 30 seconds until fragrant. The aroma filling the kitchen at this stage already feels cozy and inviting.

Cook the Spinach: Add the fresh spinach to the skillet and cook until wilted, about 2 minutes. Stir occasionally to help the spinach soften evenly. The bright green spinach adds freshness and balances the richness of the creamy sauce beautifully.

Make the Creamy Mixture: In a large mixing bowl, combine softened cream cheese, sour cream, chicken broth, onion powder, garlic powder, paprika, salt, and black pepper. Mix until smooth and creamy. Stir in the cooked chicken, spinach mixture, mozzarella cheese, cheddar cheese, and half of the Parmesan cheese. The creamy filling becomes thick, cheesy, and full of comforting flavor.

Assemble the Casserole: Spread the mixture evenly into the prepared baking dish. Sprinkle the remaining Parmesan cheese over the top. The cheese creates a golden, bubbly crust while baking that makes this casserole impossible to resist.

Bake Until Hot and Bubbly: Bake uncovered for 25–30 minutes, or until the casserole is bubbling around the edges and lightly golden on top. Allow it to rest for 5 minutes before serving. The creamy texture settles perfectly, making each scoop rich and satisfying.