Bloom the Gelatin:

In the bowl of a stand mixer, combine ½ cup cold water with the gelatin. Let sit for 10 minutes to bloom.

Make the Syrup:

In a saucepan, combine ¾ cup water, granulated sugar, corn syrup, and salt.

Heat over medium-high heat, stirring just until the sugar dissolves.

Clip on a candy thermometer and continue cooking (without stirring) until the mixture reaches 240°F (soft-ball stage).

Whip the Marshmallow Base:

Once syrup hits 240°F, carefully pour it into the gelatin mixture while mixing on low speed.

Increase speed to high and beat for 10–12 minutes, or until the mixture is thick, glossy, and tripled in volume.

Add cotton candy flavoring and gel coloring in the final minute.

Prepare the Pan:

Grease a 9x9-inch pan and dust with a mix of powdered sugar and cornstarch.

Pour the marshmallow mixture into the pan and smooth the top with a greased spatula.

Optional: Add sprinkles or swirl in a second color.

Set & Cut:

Let sit at room temperature (uncovered) for at least 6 hours or overnight.

Once set, turn out onto a surface dusted with powdered sugar + cornstarch mix and cut into cubes.

Toss each marshmallow in the dusting mix to prevent sticking.