Prepare the chicken. Bring a large pot of water to a boil over high heat. Carefully add the chicken breasts to the pot, making sure they are fully submerged with water. Return to a boil and cover pot with a tight-fitting lid. Remove from heat and allow the chicken to poach for approximately 30 minutes, or until fully cooked. Remove from the pot and set aside until cool enough to shred.
As the chicken cooks, prepare the remaining ingredients.
Shred or chop the chicken into small bite-sized cubes and transfer to the bowl of a 4 quart or larger slow cooker. Mix in the remaining ingredients (cream cheese, ranch dressing, hot sauce, black pepper, garlic powder, onion powder, green onion, cheeses).
Cover and cook on LOW for 2-3 hours or on HIGH for 1-2 hours, until hot and bubbly. Sprinkle with fresh chopped green onion, hot sauce, and additional shredded cheese, if desired. Serve hot with tortilla chips, veggie sticks, or leftover in wraps the next day!
