Homemade Marshmallows

• Combine ½ cup of the water, sugar, corn syrup, and salt, in a small saucepan.
• Cover the saucepan and cook over medium-high heat for 4 minutes.
• While the sugar is heating up, empty the envelopes of gelatin into the bottom of your stand mixer bowl and pour in the remaining ½ cup of cold water. This step is to soften the gelatin so it reacts with the hot ingredients.
  
• Then attach the whisk attachment to the mixer. Let this stand while you finish cooking the sugar.
  
• Remove the lid from the sugar mixture and, using a candy thermometer, cook the mixture until it reaches 240º F, the soft ball stage. This should take about 5 to 7 minutes. Leave the sugar mixture alone, don’t stir it.
• Once the liquefied sugar is up to temperature, turn the mixer to low speed and slowly pour the sugar mixture down the side of the bowl into the gelatin. Be careful not to pour this over the whisk while it is running or you may get splattered with hot sugar!
• When all the sugar is combined with the gelatin, turn the mixer to high speed and whip for 13 to 15 minutes. The bottom of the bowl will go from hot to lukewarm and the mixture will be very thick.
• During the last minute of whipping, add the vanilla.

Prepare the pan while the marshmallows are whipping:

• In a small bowl whisk together the powdered sugar and cornstarch.
• Spray a 13x9-inch pan with cooking spray (glass or ceramic works best), then liberally coat the bottom and sides of the pan with the cornstarch and sugar mixture. Any excess mix can be returned to the bowl.
• Cover the cornstarch/sugar mixture and set it aside as it will be used later, after the marshmallows are cut.
• Once the marshmallow mixture is fully whipped, pour into the prepared pan.
• Using an oiled spatula smooth out the top. If you'd like an even smoother surface, spread cooking oil on a sheet of plastic wrap and press the oiled side onto the marshmallows.
  
• Dust the top with some of the remaining cornstarch/sugar mixture. Set the remaining mixture aside again to use later.
• Let the marshmallows rest, uncovered on a baking rack, for at least 4 hours and up to 24 hours.
• Turn the pan upside down onto a cutting board to release the marshmallows. Or lift them out with a spatula.
  
• Run a sharp knife under very hot water and cut the marshmallows into whatever sized squares you desire. You may have to re-rinse the knife every couple of cuts.
  
• Then roll the squares in the remaining cornstarch/sugar combination. This will coat the entire marshmallow to prevent them from sticking together.