Combine the cayenne pepper, garlic powder, and salt in a small bowl and set aside. This blooming step will deepen the spice flavors and prevent them from tasting raw in the finished dip. Have your shredded Monterey Jack cheese ready—I always shred it fresh rather than using pre-shredded cheese because it melts much more smoothly without the anti-caking agents.

Pour the evaporated milk into a medium saucepan and heat over medium-high heat until it reaches a gentle boil, about 4-5 minutes. Once boiling, reduce heat to medium and gradually stir in the freshly shredded Monterey Jack cheese, stirring constantly. Continue stirring until the cheese is completely melted and the mixture thickens slightly, about 3-4 minutes. The milk's high fat content combined with the cheese creates a naturally thick, creamy base without needing any thickener.

Stir in the spice mixture from Step 1, then add the canned diced tomatoes with green chilies along with all their juices. Stir well to combine everything evenly, then simmer for 1-2 minutes to warm the tomatoes and let the flavors meld together. Remove from heat immediately—overcooking can cause the cheese to become grainy or separate.

Transfer the queso dip to a serving bowl or keep warm in a slow cooker on the lowest setting. Serve immediately with tortilla chips, crackers, or fresh vegetables for dipping.