Follow these simple steps to make your Baked Greek Chicken Casserole:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Prepare Chicken: Season the chicken breasts with salt, pepper, oregano, and basil. Heat olive oil in a skillet over medium heat and sear the chicken for 4-5 minutes on each side until golden brown. Remove from heat and set aside.
3. Cook Vegetables: In the same skillet, add diced onion and minced garlic. Sauté until the onion is translucent.
4. Combine Ingredients: In a large mixing bowl, combine the cooked orzo, sautéed onions and garlic, halved cherry tomatoes, baby spinach, feta cheese, and Kalamata olives. Mix well.
5. Layer the Casserole: In a greased 9×13 inch baking dish, spread half of the orzo mixture at the bottom. Place the seared chicken breasts on top, then layer the remaining orzo mixture over the chicken.
6. Add Chicken Broth: Pour the chicken broth evenly over the casserole to keep it moist during baking.
7. Bake: Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes. After that, remove the foil and bake for an additional 15-20 minutes, or until the chicken is cooked through and the top is lightly golden.
8. Cool and Garnish: Once cooked, remove from the oven and let it cool for about 10 minutes. Garnish with fresh parsley before serving.

These straightforward steps will guide you in creating this delectable casserole with ease.