Heat oven to 350°F. Spray 13 x 9-inch baking dish or 2 1/2-quart casserole with cooking spray.
In 12-inch skillet, heat oil (1 tablespoon) over medium-high heat. Sprinkle chicken breasts (3 large) with Old El Paso taco seasoning mix (1 package). Cook chicken in oil 6-8 minutes, turning once, until golden brown on both sides. Depending on thickness of chicken, it may not be cooked all the way through at this point but will finish baking in the oven.
In large bowl, stir together salsa con queso, half-and-half (3/4 cup) and chopped green chiles; stir in red or orange bell pepper (1 medium). Reserve one-fourth of the sauce mixture. Stir cooked white rice (2 1/2 cups) into remaining sauce mixture.
Place rice mixture in casserole; top with chicken. Top with reserved sauce mixture, then shredded Mexican cheese blend (1 cup). Cover with foil.
Bake 20 minutes; uncover and bake 10-15 minutes longer or until sauce bubbles and juice of chicken is clear when center of thickest part is cut (at least 165°F).
Cool 10 minutes. Garnish with chopped tomatoes and fresh cilantro.