Preheat oven to 350 degrees F (175 degrees C). Spray a glass baking dish with vegetable cooking spray.Advertisement
Season chicken with salt and pepper. Heat oil in a saute pan over medium-high heat; brown chicken on both sides. Place chicken in prepared baking dish. Mix together the tomato sauce and taco seasoning in a small bowl. Pour over chicken breasts. Sprinkle cheeses evenly over top.
Bake in preheated oven until chicken has fully cooked and cheese has browned, 20 to 30 minutes.