Heat the meatballs according to the package instructions.
Meanwhile, combine the sour cream, milk, mayonnaise, garlic powder and chipotle in a blender and blend until combined. Add salt and pepper to taste and blend again.
In a small saucepan, heat the butter over low heat until melted. Add the chipotle mixture and mix with a wooden spoon until combined. Heat until warm, then serve with the meatballs and garnish with the grated Parmesan and cilantro.