- Preheat oven to 375°F and grease a 9x13-inch baking dish. 
- Cut chicken into bite-sized pieces, season with garlic powder, salt, and pepper. 
- Sear chicken in olive oil for 3–4 minutes per side until lightly golden; transfer to dish. 
- In a large bowl, mix softened cream cheese, sour cream, and mayonnaise until smooth. 
- Stir in garlic, onion powder, red pepper flakes, spinach, and artichokes. 
- Spread creamy mixture evenly over the chicken in the baking dish. 
- Top with mozzarella and parmesan; add breadcrumbs if desired. 
- Cover with foil and bake 25 minutes; uncover and bake 15–20 minutes more. 
- Let casserole rest for 5–10 minutes before serving.