Place marshmallows, milk and cocoa into a small pot over medium-low heat.

Whisk constantly and make sure the marshmallows don't burn to the bottom of the pot until marshmallows have completely melted.

Add chocolate chips slowly, whisking continuously until chocolate chips have melted.

Stir in vanilla.

Set aside and let cool, whisking occasionally to prevent formation of a skin.

In a medium bowl, beat whipping cream and powdered sugar until stiff; fold into cooled chocolate mixture.

If desired, fold in chocolate chips.

Spoon into dessert bowls, wine glasses or martini glasses and freeze for several hours or until firm.