Melt the butter in a saucepan over medium heat. Whisk in the cornstarch, and let cook over the heat for one minute, while whisking. Then whisk in the evaporated milk, and continue to whisk until the milk and cornstarch mixture are well blended. Let the mixture thicken a little.

Reduce the heat to low. Stir in the cream cheese. Once the cream cheese has been mixed in, add the cheddar and monterey jack a little handful at a time. Wait for each addition of cheese to melt before you add more.

Once all of the cheese has been added and is melted, stir in the chili sauce, diced tomatoes, ketchup, smoked paprika, salt, garlic powder, onion powder, dry mustard, black pepper, and cayenne.

If you want to thicken the queso, turn the heat up just a little, and bring it to a slow bubble, while stirring frequently.