Combine sugar, cocoa, and corn starch in a saucepan off the heat. Add cream and bring to a boil over medium heat, stirring with a whisk. Let simmer 10 seconds. Pour into a bowl. Cover the surface of the sauce with plastic film. Let cool and refrigerate until ready to use. Fudge sauce keeps about one week.
In a bowl, beat cream and sugar with an electric beater until it forms firm peaks.
In dessert cups (size: approx. ½ cup or 125 ml), layer 1 tbsp. (15 ml) of cream and sugar mixture, 3 cookie pieces, 1 tsp. (5 ml) almonds, 3 marshmallows, 2 tbsp. (30 ml) fudge sauce, and 2 tbsp. (30 ml) of cream and sugar mixture. Repeat, finishing with two cookie pieces and 1 tsp. (5 ml) almonds.
Before serving, top each dessert cup with three marshmallows. Quickly brown marshmallows with a kitchen torch.
You can cover dessert cups and refrigerate them for up to two days, without marshmallow topping.