Preheat your oven to 400°F (200°C) and lightly grease a baking dish
Cut chicken into bite-sized pieces and place in a large mixing bowl
Add chopped spinach, artichoke hearts, diced bell pepper, and onion
In a separate bowl, mix mayonnaise, sour cream (or cream cheese), and lemon juice until smooth
Add minced garlic, oregano, thyme, salt, and pepper to the sauce
Stir until the mixture is creamy and well combined
Pour the sauce over the chicken and vegetables
Mix thoroughly so everything is evenly coated
Add half of the parmesan and mozzarella cheese into the mixture
Transfer the mixture into the prepared baking dish and spread evenly
Sprinkle remaining cheese over the top
Place in the oven and bake for 25–30 minutes until chicken is fully cooked
Broil for 2–3 minutes to create a golden, bubbly top
Remove from oven and let rest for 5–10 minutes
Garnish with fresh herbs if desired
Serve warm