Heat a large skillet or cast-iron pan over medium-high heat. Add the chorizo, breaking it apart with a wooden spoon as it cooks for 4-5 minutes until it develops a deep reddish-brown color and becomes slightly crispy.

Add the diced onion to the chorizo and cook for 3-4 minutes until translucent and softened. Stir in the minced garlic and diced jalapeño, cooking for another minute until fragrant.

Reduce heat to medium-low and add the softened cream cheese to the skillet. Stir constantly to break down the cream cheese and incorporate it with the chorizo mixture. Slowly pour in the milk while stirring continuously.

Gradually add the grated cheddar and Monterey Jack cheeses in small handfuls, stirring constantly in a figure-eight pattern until the mixture becomes glossy and smooth with no visible cheese chunks.

Once all cheese has melted and consistency is creamy and pourable, taste and adjust seasoning with salt and pepper. Remove from heat and stir in the fresh cilantro.