Prep the crockpot: Lightly oil or spray the insert to help prevent sticking.
Combine the base: Add cream cheese, buffalo sauce, and ranch to the slow cooker. Stir to roughly combine.
Add the chicken and cheese: Stir in the shredded chicken, cheddar, mozzarella, and blue cheese if using.
Cook low and slow: Cover and cook on Low for 2–3 hours, or on High for about 1–1.5 hours, until melty and hot.
Stir and taste: Mix well.
If you want more heat, add a splash of buffalo sauce. For extra creaminess, stir in a spoonful of ranch.
Finish: Top with green onions. Switch to Warm and serve straight from the crockpot with your favorite dippers.