01 -
Line a 9×9-inch baking pan with parchment paper, making sure it hangs over the edges a bit. Lightly grease the paper with cooking spray or a thin layer of oil to prevent sticking.
02 -
Pour 1/2 cup cold water into your stand mixer bowl and sprinkle the gelatin evenly over the surface. Let it sit for about 5-10 minutes until it becomes firm and looks like applesauce.
03 -
In a medium saucepan, mix the granulated sugar, corn syrup, salt, and remaining 1/4 cup water. Stir over medium heat until the sugar completely dissolves. Increase to medium-high heat and stop stirring. Let it boil until it reaches exactly 240°F (soft-ball stage) on a candy thermometer.
04 -
With your mixer on low speed, carefully pour the hot sugar syrup in a slow stream into the bloomed gelatin. Once it's all added, gradually increase the speed to high. Beat for 10-12 minutes until the mixture becomes thick, white, fluffy, and cools down slightly.
05 -
Add the cotton candy flavoring and a few drops of your chosen food coloring. Mix just until evenly distributed. For a fun tie-dye effect, add two different colors and give just a quick swirl with a spatula.
06 -
Working quickly before it sets, pour the marshmallow mixture into your prepared pan. Smooth the top with a greased spatula or the back of a spoon. Let it sit uncovered at room temperature for 6-8 hours or overnight to fully set.
07 -
Mix the powdered sugar and cornstarch in a small bowl. Dust your counter with some of this mixture. Flip the marshmallow slab onto the dusted surface and peel off the parchment. Dust the top with more sugar-cornstarch mix. Using a greased knife or cookie cutters, cut into squares or fun shapes.
08 -
Toss the cut marshmallows in the remaining powdered sugar mixture to coat all the sticky sides. Shake off excess in a strainer if needed. Store in an airtight container at room temperature, with parchment paper between layers if stacking.