Most importantly, preparation is key.
Before you get started, gather all your ingredients.
Add the wire whisk attachment to your stand mixer, if using one. If not, the paddle attachment will work.
Coat a 9 x 13 pan or jelly roll pan or half sheet pan, whatever you're going to use to hold your mass of marshmallow
with non-stick spray. Dust the pan thoroughly with powdered sugar. (Some recipes call for dusting the pan with half
powdered sugar and half cornstarch. I didn't have an issue with using all powdered sugar)
Spray a silicone spatula with non stick spray and set aside.
Measure the sugar, salt, light corn syrup and half cup of water. Set aside.
In a small bowl, combine three gelatin packets and a half cup cold water. Stir and set aside.
Now you're going to make the hot sugar.
Pour the sugar, corn syrup, salt, and 1/2 cup water in a saucepan. Clip your candy thermometer to the pan if using one
that stays attached. Turn on burner and cook mixture on medium heat until the sugar dissolves. Do not stir.
Raise the heat to high and cook until the syrup reaches 240 degrees on a candy thermometer. The bubbles will start
to get denser and closer together when you're nearing the softball stage or 240 degrees. On my stove it took
exactly five minutes to reach 240 degrees or the soft ball stage.
Working very quickly, remove saucepan from the heat.
Pour small bowl of gelatin into the bowl of your mixer. Turn mixer on low.
Put elbow-length oven mitts on if you have them. Pour the hot sugar into a heatproof glass measuring cup. The measuring cup will make it easier to
pour the hot sugar into the mixing bowl. With the mixer on low speed, pour the sugar onto the dissolved gelatin in the mixing bowl.
Be careful not to let any hot sugar splash onto the moving whisk. You don't want sugar burns.
Put the mixer on high speed and whip until the mixture is very thick, about 15 minutes. Add the vanilla and mix thoroughly.
Pour the marshmallow mixture into the non-metal pan you've prepared, using the spatula to thoroughly scrape the bowl. Work quickly. Once
the marshmallow cools even a bit, it's difficult to work with. You have about five seconds to get it in the pan.
Smooth the top, and dust with more confectioners' sugar. Allow to stand uncovered overnight or eight hours until it dries out.
Turn the marshmallows onto a board and cut them in squares. Dust them with more confectioners' sugar. Enjoy!