Bring a large pot of water to a boil over high heat. Add the chicken breasts and let them boil until fully cooked—about 25 minutes. Remove from the pot and allow to cool before shredding.
Preheat your oven to 350 degrees F. Spray a 9x9-inch baking pan with non-stick cooking spray.
In a medium saucepot over medium-low heat, combine cream cheese, ranch dressing, hot sauce, black pepper, and garlic powder. Whisk until blended smoothly.
Add the shredded chicken, chopped green onions, and one cup each of mozzarella and cheddar cheese to the sauce. Mix well and transfer to the prepared baking pan.
Bake for about 20–30 minutes until the cheese melts and bubbles. Switch to BROIL for an additional 2–3 minutes for a golden finish.
Let it cool slightly before serving. Pair with tortilla chips, vegetable sticks, or enjoy leftovers wrapped in tortillas.