Prepare the Chicken and Pan
Preheat oven to 400°F (200°C).
Lightly grease a 9×13-inch baking dish or large casserole pan.
Cut the chicken breasts into 1-inch cubes and place them in a large mixing bowl.
Add the Vegetables
Add the chopped bell peppers, onion, artichoke hearts, and spinach to the chicken.
If using, sprinkle in the Parmesan cheese and toss lightly to combine.
Make the Creamy Lemon Sauce
In a medium bowl, whisk together mayonnaise, minced garlic, lemon zest, lemon juice, oregano, thyme, salt, and black pepper until smooth.
Taste the sauce — add more lemon juice for tang or a touch of salt for balance if needed.
Combine Everything
Pour the lemon herb sauce over the chicken and vegetables.
Using a spatula or spoon, gently stir until everything is evenly coated.
Transfer the mixture into the prepared baking dish and spread evenly.
Place in the oven and bake uncovered for 30–35 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
The sauce should thicken slightly, and the top may turn lightly golden.
Serve
Remove from the oven and let rest for 5 minutes.
Garnish with a sprinkle of fresh herbs or extra Parmesan cheese if desired.
Serve warm with steamed rice, pasta, or toasted bread to soak up the creamy sauce.
