Preheat your oven to 400ºF/200ºC. This is a crucial step, as a hot oven will ensure your chicken cooks evenly.
Take your chicken breasts and lay them on a chopping board. Make sure the fattest part of the breast faces your knife. This positioning is vital for the next steps.
Using a sharp knife, keep it flat and parallel to your chopping board. Carefully slice through the chicken breast horizontally, opening it like a book. This should create a heart-shaped piece that is perfect for stuffing.
Cover each opened chicken breast with parchment paper and use a fry pan to gently pound it. This tenderizes the chicken and helps it cook evenly.
Repeat the pounding process with the remaining chicken breasts until they are all flattened.
Next, slice both the green and red bell peppers into thin strips. Also, peel and slice the onion into similarly sized strips. This will ensure everything cooks uniformly.
In a large heavy fry pan, place it over high heat. Allow it to get hot before adding 1 tablespoon of olive oil.
Once the oil is shimmering, toss in the sliced vegetables. Fry them for 3 to 4 minutes until they are lightly charred and starting to soften. This step brings out a wonderful caramelization.
Remove the vegetables from the heat. Immediately add in the cumin, garlic powder, salt, chili powder, smoked paprika, and dried oregano. Stir to combine and let the flavors meld.
Spread a quarter of the vegetable mixture over two of the flattened chicken breasts, topping each with 3 slices of pepper jack cheese. Then, distribute the remaining vegetables over the top and sandwich shut with the last two chicken breasts.
In the same pan used for the vegetables, add 1 tablespoon of olive oil and gently sear one side of the chicken stacks until golden brown.
Carefully flip the chicken and if your fry pan is oven-proof, place it directly into the oven. If not, transfer the chicken to a lined baking sheet.
Bake for about 15 minutes or until the cheese has melted and the chicken is cooked through. This is where the magic happens!
When done, serve your Easy Cheesy Baked Fajita Chicken with warm flour wraps, alongside avocado and sour cream, or pair it with delicious Mexican rice for a hearty meal.
