Prepare the Baking Dish: Preheat oven to 375°F (190°C). Spray the sides of a 9x13 casserole dish with non-stick spray. This step prevents sticking and makes cleanup easier while ensuring all the delicious sauce stays with your pasta rather than adhering to the pan.
Combine All Ingredients: Add orzo, cooked chicken, chicken stock, cream, seasonings, garlic, spinach, tomatoes, lemon juice and half of each cheese into the casserole dish. Mix thoroughly to combine and ensure the ingredients are evenly distributed in a flat layer. This even distribution ensures that every bite has a perfect balance of flavors and that the orzo cooks uniformly throughout the dish.
Add Cheese Topping: Sprinkle the remaining cheese evenly over the top. This creates a beautiful golden, bubbly crust as it bakes while sealing in moisture and adding rich flavor to the dish.
Bake to Perfection: Place the casserole dish in the oven and bake for 40 minutes or until the orzo is tender. The pasta will absorb the flavorful liquid as it cooks, creating a creamy texture throughout the dish.
Rest and Serve: Remove the dish from the oven and let it rest for 10 minutes to allow the pan juices to be absorbed. Mix gently with a serving spoon before serving. This resting period is crucial as it allows the dish to set slightly and for the flavors to meld together perfectly.