In the bowl of a stand mixer, whisk together the gelatin and ½ cup of the cold water to bloom. Let it sit for 8 to 10 minutes. 2½ tablespoons powdered gelatin, 1 cup cold water
As the gelatin rests, combine the remaining ½ cup water, sugar, corn syrup, and salt in a medium saucepan over medium heat. Whisk continuously and let it gently simmer for 6 to 8 minutes, until the mixture turns clear. Remove the pan from the heat. 1½ cups granulated sugar, ¾ cup light corn syrup, ½ teaspoon kosher salt
Fit the mixer with the whisk attachment and set it to low speed. Slowly pour in the hot sugar mixture. After it is fully added, whisk for another minute to combine. Then increase the speed to high and beat for about 10 minutes, until the mixture becomes thick, fluffy, and bright white like marshmallow.
Mix in the cotton candy flavoring and whisk for about 1 more minute. Divide the marshmallow mixture evenly between two bowls. Tint one bowl pink and the other blue using food coloring.2 teaspoons cotton candy flavoring, pink and blue food coloring
Lightly coat a 9×13-inch pan with powdered sugar to keep the marshmallows from sticking. Spoon the marshmallow mixture into the pan, alternating the pink and blue colors. Use a rubber spatula to smooth the top evenly. Sprinkle the remaining powdered sugar over the surface, cover with plastic wrap, and let it set for 8 to 12 hours. ¾ cup powdered sugar
After the marshmallows have fully set, lift the slab out of the pan and place it on a cutting board. Brush off any extra powdered sugar, then slice into 1 inch squares. Serve and enjoy.
