Line a 9X9 baking dish with parchment paper or wax paper and spray the paper with a non-stick cooking spray.  Carefully dust the paper in the pan with cornstarch to help the marshmallows from sticking to the pan and the liner.

Place the gelatin in a large bowl for a stand up mixer. Pour 1/2 cup of the water on top. Set aside and let the water soak into the gelatin.

While the gelatin is setting, combine the remaining water, corn syrup and sugar in a saucepan. Stir together and bring the mixture to a boil. Boil for about 1 minute or until the sugar has dissolved and the mixture reaches 240 degrees F (check with a candy thermometer).

Pour the corn syrup mixture into the bowl with the gelatin. Beat with a stand up mixer with the whisk attachment.  Mix for 10-12 minutes until stiff peaks are easily formed in the mixture.

Add in the salt and vanilla extract and mix until combined.

Pour the mixture into the prepared pan. The mixture will be sticky so make sure to grease a spatula and wet your fingertips to prevent the mixture from sticking.

Cover the pan with plastic wrap and let it sit at room temperature for 4 hours until the marshmallows are set.

In a separate shallow bowl, whisk together the powdered sugar and cornstarch for dusting of the marshmallows.

Carefully remove the marshmallow slab from the pan and place the slab on a cutting board dusted with the dusting mixture.

Use a large oiled kitchen knife (to prevent it from sticking) to cut the marshmallow slab into 1 inch squares.

Roll the marshmallows in the dusting mixture so that they do not stick together. Then they are ready to serve and enjoy!