Line a 9” x 9” baking pan with parchment paper and coat with nonstick cooking spray. Set aside.

Place gelatin and ½ cup of water into the bowl of a standing mixer fitted with the whisk attachment. Stir to combine then set aside.

In a small saucepan, combine remaining ½ cup water, sugar, corn syrup, and salt. Stir over medium heat until sugar dissolves, about 7 minutes. Increase the heat to high and let the mixture cook, without stirring, until it reaches 240F on a candy thermometer. Remove from heat.

With the mixer on low speed, gradually pour the hot syrup into the bowl. Increase to high speed and continue mixing until the mixture has cooled and is thick and fluffy. You’ll start to see marshmallow ribbons pulling away from the sides of the bowl, which means it’s almost ready! Add the vanilla extract and mix until it’s evenly distributed.

Use a rubber spatula to spread mixture into the prepared pan. Gently shake the pan from side to side to evenly distribute the mixture and get a smooth, flat top.

Sift the powdered sugar and cornstarch together, then sprinkle about 2 Tbsp. of the mixture on top of the marshmallows. Place the remaining powdered sugar mixture in a large Ziplock bag and set aside. Let marshmallows sit for at least 4 – 6 hours or overnight (if you can wait, overnight is preferred!).

When the marshmallows have set, flip the pan and place marshmallows on a cutting board. Spray a knife with nonstick cooking spray and cut into squares (or use a cookie cutter for fun shapes!). Place a few squares into the bag of powdered sugar/cornstarch and shake until coated. To remove any excess, bounce the marshmallow in a fine mesh strainer. Repeat until all marshmallows are coated. Store in an airtight container.