Prepare the Square Pan - Generously dust the square pan with powdered sugar.
Make the Gelatin - In a small mixing bowl, combine the gelatin with eight tablespoons of cold water.
Heat Granulated Sugar and Vanilla - In a large saucepan over medium heat, add the granulated sugar and 1/2 cup of cold water. Cook the mixture, stirring regularly until the sugar is dissolved.
Add the Gelatin - Add the gelatin to the sugar water. Bring the mixture to a boil and then remove the mixture from the heat. Carefully for the mixture into a large mixing bowl and allow it to partially cool.
Add the Salt and Vanilla Extract - To your mixture, add the salt and vanilla extract, mixing together until combined. You may substitute the vanilla extract for another flavor if desired.
Beat Marshmallow Mixture With an Electric Mixer - Using an electric mixer, beat the marshmallow mixture. Beat the mixture for about 10-15 minutes, or until it has reached a soft texture and has doubled in volume.
Pour Into Pan and Let Set - Carefully pour your marshmallow into the prepared pan. It should be about 1/2 inch thick. Let the marshmallow sit so it can fully cool.
Cut and Serve - Once the marshmallow does not stick to your fingers, it is ready to serve. Cut it with a sharp knife into about 1 1/2 inch squares. Roll the marshmallow squares around in powdered sugar and serve.