Prep your ingredients: Chop the cheese into small cubes or shred it so it melts quickly. Mince the onion, jalapeño, and garlic as finely as possible for a smooth dip.
Sweat the aromatics: In a small saucepan over low heat, melt the butter.
Add the onion and jalapeño with a pinch of salt. Cook 3–4 minutes, stirring often, until soft and fragrant. Add the garlic and cook 30 seconds more.
Keep the heat low to avoid browning.
Add the liquid base: Pour in the evaporated milk and stir in the cumin. Warm gently until steaming, not boiling. Do not let it simmer hard—high heat can cause the cheese to separate later.
Incorporate the cheese gradually: Add a small handful of cheese and stir with a spatula or whisk until fully melted and smooth. Continue adding the cheese in small batches, stirring constantly.
Patience here creates that ultra-silky texture.
Adjust consistency: If the dip is too thick, add a splash of milk or water until it’s pourable but still coats a chip. If it’s too thin, add a bit more cheese.
Season and finish: Stir in the diced green chiles if using. Taste and add salt as needed.
Fold in the cilantro just before serving for a fresh note.
Serve warm: Transfer to a warm bowl, small slow cooker, or fondue pot to keep it smooth and melty. Garnish with a little extra cilantro or a sprinkle of chili powder if you like.