Prep your slow cooker: Lightly spray the insert with nonstick spray. This helps prevent sticking and makes cleanup easier.
Add the base: Place the cubed processed cheese, shredded Monterey Jack or Pepper Jack, and cream cheese into the slow cooker.
Pour in liquids and seasonings: Add the evaporated milk, the entire can of diced tomatoes with green chiles, minced jalapeño (if using), cumin, chili powder, garlic powder, onion powder, and a pinch of salt and pepper.
Cook low and slow: Cover and cook on Low for 1.5 to 2 hours, stirring every 30 minutes.
The cheeses should melt evenly and the mixture will become smooth and creamy.
Add mix-ins: If using cooked chorizo, ground beef, beans, or corn, stir them in once the cheese is melted and smooth. Cover and cook for another 15 minutes to warm through.
Finish with brightness: Stir in lime juice, then taste and adjust salt, pepper, or heat as needed. If it’s too thick, thin with a splash of evaporated milk until it reaches your ideal consistency.
Serve warm: Switch the slow cooker to Warm, garnish with cilantro or green onions, and set out chips and toppings.
Stir occasionally to keep it silky.