Brown ground beef in a skillet over medium-high heat, stirring often, 8 to 10 minutes or until meat crumbles and is no longer pink; drain.
Combine pepper-Jack cheese product, American cheese, and milk in a large microwave-safe bowl. Microwave at HIGH 8 minutes or until cheese is melted, stirring every 2 minutes. Stir in ground beef, tomatoes, and cilantro. Garnish, if desired. Serve with desired dippers.
Note: For testing purposes only, we used Velveeta Pepper Jack for pasteurized prepared cheese product.