Place chicken breasts, taco seasoning, ranch mix and chicken broth into a small crockpot.
Cook on low for 5 to 6 hours. Remove chicken breasts, shred with two forks, then return meat to the crockpot with the juices.
Scoop up chicken with tongs, letting excess juices drip off and place the chicken into a crunchy taco shell with cheese, lettuce, and ranch dressing, if desired.