Add the butter to a saucepan and melt over medium heat. Once melted, add the remaining sauce ingredients and simmer for 1 minute. Remove from heat and allow to cool slightly.
To Make the Buffalo Chicken Dip
Preheat oven to 375F. Add the chicken breast to a large bowl and shred using a hand mixer. If you don't have a hand mixer, you can use 2 forks. Set aside.
In a separate bowl, add the cream cheese, blue cheese dressing, buffalo sauce, sour cream, parsley and garlic salt, and mix until well combined. Set mixture aside.
In the bowl with the chicken, add in the shredded cheddar and mozzarella cheese, but reserve ½ cup of the cheddar cheese for the topping. Mix by hand until combined. Then mix in the cream cheese mixture.
Pour the mixture into a baking casserole dish, sprayed with non-stick spray. Sprinkle the reserved ½ cup of cheddar cheese over the top of the dip, then add the blue cheese crumbles.
Bake for 20 minutes at 375F, or until the cheese is slightly golden brown. Bake an additional 5 minutes at 400F. Allow to cool slightly before serving with celery sticks or homemade cheese crackers.