Preheat the broiler.
On a foil-lined baking sheet, place half of the marshmallows in a single layer; broil until charred, about 3 minutes. Transfer to a plate to cool. Place the remaining marshmallows on the sheet and roast just until toasted, about 2 minutes. Transfer to a plate and let cool. In a blender, mix the ice cream, milk, sour cream and charred marshmallows. Serve topped with the toasted marshmallows.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.