Put frozen chicken breasts in the bottom of the crockpot, top with spices and veggies.
Pour tomatoes or Rotel over all.
Cook for 6-8 hours on low, or 4-5 hours on high, turning breasts over at least one time. This can be done toward the end if necessary just to make sure it doesn't dry out.
When fully cooked, shred chicken.
Serve on tortillas or chips, with toppings of your choice, tomatoes, sour cream, cheese, lettuce. Enjoy!