Preheat your oven to 400°F (200°C). This ensures that your casserole cooks evenly.
In a baking dish, season the chicken breasts generously with fajita seasoning and vegetable oil. Make sure the seasoning is well distributed; I love using my hands to massage the spices into the meat for maximum flavor.
Next, layer the sliced bell peppers and onion over the seasoned chicken. This not only adds flavor but also creates a colorful presentation.
Sprinkle a little more fajita seasoning over the top for added flavor, then cover everything with a generous layer of shredded cheese. The cheese will melt beautifully in the oven.
Now, place the baking dish in the oven and bake uncovered for about 25 to 30 minutes. You’ll know it's ready when the chicken is cooked through and the cheese is bubbling.
Once done, remove the casserole from the oven. Let it sit for a few minutes before serving. This allows the flavors to settle.
Serve immediately, garnished with fresh cilantro leaves if desired. This adds a delightful freshness to every bite!
