Preheat your oven to 375 degrees Fahrenheit and spray a medium-sized casserole dish with cooking spray.
Rub the taco seasoning onto the chicken breasts on all sides and place them in the prepared casserole dish.
Pour the salsa on top and spread it out over the chicken breasts.
Top with the shredded cheese and bake for about 20-25 minutes, or until an instant read thermometer inserted into the chicken breast reads 165 Fahrenheit (74 Celsius).
Serve hot from the oven with sour cream and sliced jalapenos.