In a bowl, combine gelatin with ½ cup of cold water.
Take a saucepan and combine the remaining 1/2 cup of cold water, granulated sugar, salt, and corn syrup. Cover the sugar syrup and allow it to cook for 3 to 4 minutes.
Uncover the mixture and, using a candy thermometer, check the temperature of the liquid. Once the mixture reaches 240 degrees, turn the heat off.
Now turn on your stand mixer or take the help of an electric mixer, and slowly pour the sugar syrup into the gelatin. Increase the speed to high and continue whipping until it becomes thick. Add the vanilla extract or vanilla bean. This will take you about 12-15 minutes.
In a separate small bowl, whisk confectioners' sugar and cornstarch together.
Coat a 13 by a 9-inch baking dish with non-stick cooking spray. Then add the cornstarch mixture and coat the sides and bottom of the pan nicely.
Now pour the prepared marshmallow mixture into the pan using a lightly oiled spatula to spread it evenly in the pan.
Dust the top with the remaining sugar and cornstarch mixture to lightly cover. Allow the marshmallow to sit uncovered for 4 hours or overnight.
Using a small cookie cutter, cut the marshmallows into circles and transfer them to a tray lined with parchment.
Your marshmallows are ready. Now comes the fun part. All you have to do is decorate them using piping bags filled with colored chocolates.
You can decorate the marshmallow toppers by making eyes and a smile, or you can give them a snowman makeover by making a scarf. The possibilities are many, so bring out your best creativity.