Line a plate with parchment paper; set aside. Put the candy melts in a microwave-safe bowl and microwave in 30-second intervals, stirring after each, until melted, about 3 minutes. Spread on the cones with an offset spatula; place upside-down on the prepared plate.
While the coating is still wet, press mini marshmallows around the base and 1 marshmallow on the tip of each cone, using more of the melted candy as glue, if needed. Freeze until set, about 1 hour.
Scoop 4 large balls of ice cream onto plates. Gently top each scoop with a cone; decorate the base of the ice cream with whipped cream.