2 large poblano chilies
1/2 pound white American cheese, cut into 1/2-inch cubes
1/2 pound Monterey Jack cheese, cut into 1/2-inch cubes
2 teaspoons cornstarch
1 tablespoon olive or vegetable oil
1 teaspoon minced fresh garlic, about 1 medium clove
1/2 teaspoon ground cumin
1/4 teaspoon chipotle chili powder
1/4 teaspoon cayenne pepper
5 ounces evaporated milk
3 tablespoons finely chopped fresh cilantro
2 tablespoons finely chopped scallions
Kosher salt, to taste