Place the chicken breasts in the bottom of the slow cooker.
Add the diced onion, minced garlic, drained beans, green chiles, corn, cumin, oregano, chili powder, salt, and pepper on top of the chicken.
Pour the chicken broth over the ingredients and stir gently to combine, ensuring the chicken is covered.
Cover and cook on LOW for 6-8 hours or on HIGH for 3-4 hours, until the chicken is tender and cooked through.
Remove the chicken breasts to a plate or cutting board and shred nicely using two forks.
Return the shredded chicken to the slow cooker.
Stir in the cubed, softened cream cheese and half and half (if using).
Cover and cook on HIGH for an additional 15-20 minutes, stirring occasionally, until the cream cheese is fully melted and incorporated into the broth.
Taste and adjust salt and seasonings if necessary.
Serve warm, topped with fresh cilantro, avocado slices, lime wedges, or tortilla chips.