• Melt butter in a medium saucepan over medium-low heat. Add onion and cook until soft, about 8-9 minutes. Add garlic and cook 30 seconds, just until fragrant.
• Pour in evaporated milk and warm gently — do not boil.
• Add white American cheese and stir until fully melted and smooth.
• Add shredded Pepper Jack gradually, stirring constantly until smooth. Stir in green chiles.
• Keep warm on low heat, stirring occasionally. Top with cilantro and, if desired, diced Roma tomatoes and pickled jalapeños.

If adding chorizo, ground beef, or sausage:

• In a saucepan or skillet over medium heat, brown the chorizo, sausage, or ground beef, breaking it up finely. Once fully cooked, drain excess grease. If using ground beef, it needs to be seasoned with salt and pepper.
• Stir in half of the chorizo into the queso and place the remaining on top of the queso as garnish.