In a small slow cooker, add the cheese cubes as well as both cans of the tomatoes with chilies, including the liquid from the cans. Set the slow cooker to low and let melt, stirring occasionally, until completely melted, about 30 minutes. Keep warm until ready to serve.
Serve with tortilla chips, flour tortillas or as a topping for fajitas, nachos or tacos.
For a heartier version, add one pound of browned ground beef to the mix.