Prep the chicken: Shred cooked chicken into bite-size pieces. Avoid large chunks so the dip scoops easily.
Layer the base: Add cream cheese, buffalo sauce, ranch dressing, and butter to the slow cooker.
Sprinkle in garlic and onion powders.
Add the chicken: Stir in the shredded chicken until everything is coated. It’s okay if the cream cheese isn’t fully melted yet.
Top with cheese: Sprinkle cheddar and Monterey Jack over the mixture. Reserve a small handful for later if you want a gooey melted top.
Cook low and slow: Cover and cook on Low for 2–3 hours or High for 1–1.5 hours, until hot and bubbly.
Stir and season: Open the lid, stir well to combine, and taste.
Add salt and pepper as needed. If using reserved cheese, sprinkle it on, cover for 5–10 minutes to melt.
Garnish and serve: Top with green onions and optional blue cheese crumbles. Switch to the Warm setting and serve straight from the slow cooker.