Heavily grease a cookie sheet or 9×13 pan.
Pour cold water into mixing bowl and sprinkle gelatin over cold water. Cover and set aside. In a saucepan, combine sugar, 180mL corn syrup, and water. Allow to cook over medium heat until it reaches 240F. Do not stir! Remove from heat and add remaining 60mL corn syrup.
Using the whisk attachment, begin to beat the gelatin mixture. Slowly and steadily add the sugar mixture. Turn up the mixer and beat until the mixture triples in volume and becomes stiff and sticky. During this mixing, you can add whatever flavor you choose! Spread the mixture evenly into your greased pan and allow to cool for three hours. After cooled, spread powdered sugar across the top and flip the sheet of marshmallow onto a clean surface. Coat the other side with powdered sugar, then use either a greased knife or cookie cutter to cut your marshmallows into whatever shape you would like!
Enjoy in s’mores, hot chocolate, or just because!