Place the 4 boneless skinless chicken breasts in the crockpot; they can be frozen or thawed.
Add the drained black beans, drained corn, salsa, and taco seasoning (if using) on top of the chicken.
Cover and cook on low for about 4 to 5 hours, until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
Remove the chicken from the crockpot and shred it with two forks or tongs.
Return the shredded chicken to the crockpot, place the softened cream cheese on top, cover, and let sit for about 30 minutes.
Stir the cream cheese into the mixture until fully combined and creamy.
Serve the Fiesta Chicken over rice or in warm flour tortillas.