Spray a 9x13 pan with cooking spray, line with parchment paper

Coat the parchment paper with 1/4 cup confectioners' sugar using a sieve to dust

Add 1/2 cup water and the gelatin to a mixing bowl from a standing mixer

Add the sugar, corn syrup, salt and 1/2 cup water to a medium saucepan

Cook until 238 degrees using a candy thermometer

When the syrup reaches 238 slowly pour into the mixing bowl with the mixer on low speed. Using the whisk attachment

Increase the speed to high and beat for 10-15 minutes until thick and creamy

Add the vanilla

Scrape the batter into the prepared pan, smooth the top and cover with the rest of the confectioners' sugar - using a sieve

Leave the pan to and dry out for 8 hours or overnight

Using a sharp knife, cut the marshmallows into squares ( see pictures above)

Coat the sticky sides in more confectioners' sugar

Store in an airtight container