In a large skillet, heat the olive oil over medium heat. Add minced garlic and sauté for about 1 minute until fragrant.
Add the chopped spinach to the skillet and cook until wilted, about 3-4 minutes. Remove from heat and let cool slightly.
In a large mixing bowl, combine the shredded chicken, ricotta cheese, cream cheese, ½ cup mozzarella cheese, and ½ cup parmesan cheese. Stir in the cooked spinach, cooked pasta, onion powder, garlic powder, Italian seasoning, salt, and pepper. Mix well until all ingredients are fully incorporated.
Transfer the chicken and spinach mixture into a greased 9x13 inch casserole dish. Spread evenly.
Top the casserole with the remaining mozzarella and parmesan cheese.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Let the casserole cool for a few minutes before slicing and serving.
Notes
Let the casserole cool slightly before serving for easier slicing.