In large micro safe container, warm milk in microwave until hot, I usually stir at least once. (Microwaves vary). Mix sugar & cornstarch together and stir in hot milk.
Whisk eggs and add small amount of hot milk then add to milk mixture. Microwave until thick and coats spoon (stir every 3-4 min).
When thickened, pour into another pan containing marshmallows using a strainer. Whisk until marshmallows are melted and stirred in well. Let cool, refrigerate. Before serving, stir well. A dollop of vanilla ice cream or whipping cream topped with a cherry sets it off.