Spray CrockPot with cooking spray.
Cube the cream cheese and place into CrockPot; then add remaining ingredients (begin with 1 cup of mayonnaise, then add more if needed during last 30 minutes of cooking time for creamy texture).
Stir ingredients to combine.
Place lid on CrockPot and cook on LOW setting for 2 hours; stir every 20-30 minutes to make sure mixture is combined and cheese melts evenly.
If serving as a party dip, turn CrockPot setting to WARM and serve. Otherwise, serve immediately with your choice of breads or dippers.
Feel free to change up the cheeses and add a hot mustard or splash of hot sauce, if desired.