Place the chicken breasts in the slow cooker in an even layer. For the most consistent cooking, use breasts that are close in size and thickness.

Sprinkle the taco seasoning evenly over the chicken. Add the chunky salsa, drained black beans, and drained corn on top; the ingredients may be layered without stirring.

Cover and cook until the chicken reaches 165°F internally and shreds easily, about 6–8 hours on LOW or 3–4 hours on HIGH. Cooking time can vary with chicken size and slow-cooker performance, so use a thermometer to confirm doneness.

During the final 15–30 minutes of cooking, add the cubed reduced-fat cream cheese. Keeping it out until the end helps it blend into a smoother sauce and reduces the chance of separation.

Shred the cooked chicken with two forks directly in the slow cooker. Stir the chicken, vegetables, beans, salsa, and cream cheese together until the cream cheese is fully incorporated and the mixture is creamy.

Serve the fiesta chicken hot by itself, over rice, or inside low-calorie tortillas. Finish with optional cilantro, chopped tomatoes, jalapeno, or a small amount of reduced-fat cheese.