In a large skillet over medium heat, add olive oil. Once hot, add the diced chicken and season with Italian seasoning, salt, pepper, and red pepper flakes if using. Sauté for about 5-7 minutes, until the chicken is cooked through and lightly browned.
Stir in the minced garlic and cook for an additional 1-2 minutes until fragrant.
In a large mixing bowl, combine the cooked chicken, orzo pasta, chicken broth, drained diced tomatoes, chopped spinach, and sundried tomatoes. Mix until well combined.
Transfer the mixture to a greased baking dish.
Cover the baking dish with aluminum foil to prevent drying. Bake in the preheated oven for 20 minutes.
Remove the foil and stir the mixture gently. Sprinkle the shredded mozzarella and grated Parmesan evenly on top.
Bake uncovered for an additional 15-20 minutes, until the cheese is melted and bubbly.
Remove from the oven and let it rest for 5 minutes before serving.
Notes
Let the dish rest before serving for better flavor.