In a large skillet, heat olive oil over medium heat. Add the chopped spinach and sauté until wilted, about 3 minutes. Remove from heat and set aside.
In a large mixing bowl, combine the shredded chicken, wilted spinach, cream cheese, mozzarella cheese, sour cream, garlic powder, onion powder, salt, and pepper. Mix until well blended.
Transfer the chicken and spinach mixture to a greased 9x13 inch baking dish, spreading it evenly.
If desired, sprinkle breadcrumbs over the top for added crunch (optional).
Finally, sprinkle the grated Parmesan cheese evenly on top of the casserole.
Bake in the preheated oven for 25-30 minutes, or until the cheese is bubbly and golden brown.
Remove from oven and let it sit for about 5 minutes before serving.
Notes
Serve hot, garnished with fresh parsley or basil for a pop of color.