01 - Combine milk and heavy cream in a medium saucepan over medium heat. Bring just to a simmer without boiling.
02 - Whisk in cream cheese until completely melted and smooth.
03 - Gradually stir in shredded white American cheese, a handful at a time, whisking constantly until fully melted and the dip is smooth.
04 - Add diced jalapeño, green chilies, onion, and garlic. Cook for 2-3 minutes, stirring frequently, until vegetables soften.
05 - Stir in ground cumin, chili powder, salt, and white pepper. Adjust seasoning to taste.
06 - Reduce heat to low to keep warm. Stir occasionally and whisk in a splash of milk if the dip thickens too much. Serve warm with tortilla chips, fresh vegetables, or as a nacho topping.