Lightly grease your slow cooker.
Place the chicken breasts in the bottom. Sprinkle evenly with the ranch seasoning and taco seasoning.
Add the chopped onion, Rotel, cream cheese, sour cream, and chicken broth.
Cover and cook: HIGH for 3–4 hours or LOW for 6–7 hours until the chicken is fully cooked and tender.
Remove the chicken and shred it. Return the shredded chicken to the slow cooker.
Stir in the Colby Jack cheese until fully melted and creamy.
Let sit for 5–10 minutes to thicken, if desired.
Serve in tortillas as tacos or folded into quesadillas.
Top with Pico de Gallo, if desired.