Combine milk, margarita mix and sugar in a blender. Pour into the freezer bowl of an ice cream maker and let mix until mixture thickens, about 25 minutes. (The frozen sherbet can be stored in the freezer in an airtight container.)

Top each brownie with a scoop of sherbet and decorate with nonpareils. (Please note, on the episode we rolled the sherbet in Dippin' Dots, which are pastel-colored flash-frozen globules of ice cream. They are not typically sold in supermarkets because the sub-zero temperatures required to store them are generally not achievable in home freezers, so we are using nonpareils instead.)