In a slow cooker set to high heat, place the processed cheese and milk. Cover and, stirring occasionally, cook until the cheese has melted and is well blended with the milk.
Place ground pork sausage in a medium skillet. Cook over medium high heat until evenly brown. Mix in white onion. Cook and stir until onion is translucent. Remove from heat and drain.
Stir sausage mixture into the cheese mixture. Reduce heat to low. Mix in salsa and black beans. Continue cooking, stirring occasionally, approximately 1 hour.
Garnish with green onions and serve with tortilla chips.
