Place chiles on a foil-lined baking sheet, and broil 10 minutes or until the chiles are blackened, turning occasionally. Place chiles in a zip-top plastic bag; seal. Let stand 15 minutes. Peel chiles; cut in half lengthwise, discarding the seeds and membranes. Cut into 1/2-inch pieces; set aside.
Heat 1 teaspoon butter in a small skillet over medium heat. Add onion and garlic; sauté 5 minutes. Remove from heat.
Combine onion mixture, milk, cornstarch, and corn in a blender or food processor, and process mixture until smooth.
Heat 1 teaspoon butter in a large saucepan over medium-high heat. Add corn mixture to pan (mixture will boil vigorously), and cook for 3 minutes. Add Chicken Stock, and bring to a boil. Stir in chiles, cream cheese, salt, and pepper; reduce heat, and cook for 5 minutes or until cheese melts. Serve with Salsa Verde.