Preheat the oven to 400°F and grease a baking dish.
In a bowl, mix the cream cheese, tomato sauce, chicken stock, and fajita seasoning until smooth.
Toss the cubed chicken with the remaining fajita seasoning, salt, and pepper.
Add the seasoned chicken to the prepared baking dish, then spread the creamy mixture evenly over it.
Distribute the sliced bell peppers and minced onion over the top.
Sprinkle the shredded cheese generously over everything.
Bake for 15–25 minutes, or until the chicken is cooked through.
Broil briefly for a golden, bubbly top if desired.
