Place ½ cup of the water and gelatin in the bowl of a stand mixer. Meanwhile, in a small saucepan remaining ½ cup water, sugar, corn syrup, and salt. Cook over medium heat until the mixture reaches 240˚ F. about 12-15 minutes.
Whisking at low speed, slowly add the syrup to the bowl with the gelatin. Once all of the syrup has been added, increase the speed to high and whip until the mixture is very thick and lukewarm, about 12-15 minutes. Blend in the vanilla.
Combine the confectioners’ sugar and cornstarch in a bowl and whisk to blend. Lightly grease a quarter pan. Coat the bottom and sides of the pan well with a dusting of the sugar-cornstarch mixture, reserving the rest. Spread the marshmallow mix it into an even layer in the prepared pan. Let stand uncovered at least 4 hours or up to overnight.
Remove the marshmallow slab to a cutting board. Sprinkle a layer of the sugar mixture over the top and spread out gently to coat lightly. Use a lightly greased round cookie cutter (approximately 1.75 inches in diameter) to cut out rounds of the marshmallow, dipping in the sugar mixture and re-greasing as needed to prevent sticking. Lightly coat the cut edges of each marshmallow round in the sugar mixture to prevent sticking together.
Use the flat end of a toothpick dipped in the melted chocolate to dot the eyes and mouth onto each snowman. Add the orange icing to a pastry bag fitted with a small round tip to create little carrot noses for each snowman.