Preheat your oven to 375°F (190°C) to ensure even cooking.
In a large skillet, heat the vegetable oil over medium heat. Add the diced onion, red bell pepper, and green bell pepper, cooking until tender, about 3-4 minutes. Add the chicken pieces, sprinkle with fajita seasoning, and cook until no longer pink, about 5-7 minutes.
Open the can of biscuits and cut each biscuit into quarters to create fluffy 'bubbles' for the bake.
Remove the skillet from heat and combine the sautéed chicken and vegetables with the quartered biscuits and 1 cup of shredded cheese in a large mixing bowl. Gently toss until well coated.
Transfer the mixture to an oven-safe baking dish, sprinkle the remaining cheese on top, and bake for 25-30 minutes until golden brown and bubbling.
Remove from the oven and let cool for a few minutes before serving hot, garnished with fresh cilantro or sour cream if desired.
