Preheat the oven to 400ºF.
Cook the sausage in a 12-inch cast iron over medium heat, breaking it apart. Add onions and green chiles, and cook until the onions are translucent.
Sprinkle on both cheeses, cream cheese and cook, stirring until it melts—about 2-3 minutes.
Place into the oven and start watching it about 4 to 5 minutes in. You want to bake it until the cheese is totally melted, hot, and slightly bubbling.
Remove from the oven, sprinkle and serve immediately with tortilla chips. Optional toppings: tomatoes, cilantro, and fresh jalapeño.