Step 1: Preheat the Oven and Prepare the Baking Dish

1. Preheat the Oven:
   Preheat your oven to 375°F (190°C). This temperature ensures that your casserole will cook evenly and the cheese will melt perfectly.
2. Grease the Baking Dish:
   Lightly grease a 9×13-inch baking dish with non-stick cooking spray or a bit of olive oil. This step prevents the casserole from sticking and makes cleanup easier.

Step 2: Cook the Chicken and Vegetables

3. Heat the Olive Oil:
   In a large skillet, heat the olive oil over medium-high heat. The oil should be hot enough to sear the chicken without burning it.
4. Cook the Chicken Strips:
   Add the chicken strips to the skillet and cook for about 5-7 minutes, or until they are browned and no longer pink in the center.
   Cooking Tip: To ensure the chicken cooks evenly, avoid overcrowding the pan. Cook in batches if necessary.
5. Add the Vegetables:
   Once the chicken is cooked, add the sliced red, yellow, and green bell peppers, along with the onion, to the skillet. Cook for an additional 5 minutes until the vegetables are tender and slightly caramelized.
6. Season the Mixture:
   Sprinkle the fajita seasoning over the chicken and vegetable mixture, stirring well to coat everything evenly. This seasoning adds the classic fajita flavor to the dish.

Step 3: Assemble the Casserole

7. Spread the Cooked Rice:
   In your prepared baking dish, spread the cooked rice evenly across the bottom. The rice adds a hearty base to the casserole and soaks up all the delicious juices.
8. Layer the Chicken and Vegetables:
   Spoon the chicken and vegetable mixture over the rice, spreading it out to create an even layer.
   Helpful Tip: For extra flavor, you can add a layer of black beans or corn on top of the rice before adding the chicken and vegetables.
9. Add the Salsa and Sour Cream:
   Pour the salsa over the chicken and vegetables, spreading it evenly with a spoon. Then, dollop the sour cream over the salsa. The salsa adds a tangy kick, while the sour cream brings a creamy richness to the dish.
10. Top with Cheese:
    Sprinkle the shredded Mexican cheese blend over the entire casserole. This cheese layer will melt beautifully, creating a gooey, bubbly topping.

Step 4: Bake the Casserole

11. Bake the Casserole:
    Place the baking dish in the preheated oven and bake for 20-25 minutes, or until the cheese is fully melted and bubbly.
    Baking Tip: If you prefer a golden-brown crust, you can broil the casserole for the last 2-3 minutes, keeping a close eye on it to prevent burning.
12. Cool and Serve:
    Once the casserole is done, let it cool for a few minutes before serving. This helps the layers set and makes it easier to slice and serve.
13. Garnish and Enjoy:
    Garnish with fresh cilantro, chopped green onions, or a squeeze of lime juice for a burst of freshness. Serve with a side of guacamole, extra sour cream, or tortilla chips for added texture and flavor.