Preheat oven to 400 F. Lightly grease a 9x13-inch baking dish with non-stick cooking spray.
Evenly spread the uncooked rice into the baking dish. Nestle the chicken tenderloins or chicken breasts into a single layer.
In a mixing bowl, whisk together the cream of poblano soup with the chicken stock, and taco seasoning. Once mixed well, pour over the chicken and rice.
Wrap the baking dish tightly with foil and bake in the preheated oven for 1 hour and 15 minutes, or until chicken is cooked through and rice is fork tender. Season with salt and pepper to taste.
Serve Dump and Bake Taco Chicken with shredded cheddar cheese and sour cream garnish.