Pour 1 can of the mild green chile enchilada sauce into the slow cooker. Then place the chicken breast on top of the sauce and pour the additional can on top of the chicken breast. Set on low and cook for 8 hours.
Once the chicken breast are cooked, remove the chicken breast from the slow cooker and shred with 2 forks. Before placing the chicken breast back in the slow cooker add the whipped cream cheese and cilantro. Mix until melted and fully incorporated. Add the shredded chicken back to the slow cooker and mix well.
Warm the flour tortillas in a microwave with a damp cloth draped over them for 30 seconds. Once tortillas are cooked, begin spooning shredded chicken on to taco shells. Divide avocado slices evenly, and enjoy.