In a small bowl, whisk together One part cornstarch to one part powdered sugar. Cover and set aside until needed.
Prepare a 9×13 baking sheet by covering it with aluminum foil, making sure that some of the foil comes over the edges of the pan allowing you to remove the marshmallows easier when they are dry.
In a small bowl, sprinkle the gelatin over the 1/2 cup of cold water to dissolve and soften. If using leaf gelatin, soak the leaves in about 2 cups cold water.
In a small saucepan, whisk together the sugar and corn syrup with the remaining 1/3 cup of water. Attach a candy thermometer to the side of the pan and place over medium-to-high heat.
Attach a candy thermometer to the side of the pan and place over medium-to-high heat.
In a large mixing bowl with a hand mixer or in a stand mixer with a paddle attachment, pour in the egg whites and beat on low speed until frothy. Add the pinch of salt.
*Note: An easy way to get egg whites to room temperature is simply placing them eggs in a medium size bowl or container and fill it up with room temp. water. Allow eggs to sit in the water for 10-15 minutes. Instant room temp. eggs!
When the syrup reaches about 210 F, increase the speed of the mixer to high and beat the whites until they are thick and fluffy, about a minute.
When the syrup reaches 245 F, while the mixer is running on high speed, slowly pour the hot syrup into the whites, being careful not to pour the syrup on the whisk.
Scrape the prepared gelatin and water into the pan that you used for the syrup, or put the gelatin sheets and 2 tablespoons of the water into the pan and swirl it to dissolve. The heat from the pan will allow the gelatin to dissolve.
Pour the liquified gelatin slowly into the whites as they are whipping. Add the vanilla extract and continue to whip for 10-12 minutes, until the mixture
Add the vanilla extract and continue to whip for 10-12 minutes, until the mixture feels completely cool when you touch the outside of the bowl.
Using a sifter, dust a 9×13 baking sheet evenly and completely with a generous layer of the sugar/starch mixture. Make sure there are absolutely no bare spots. Use a spatula to spread the marshmallows in a layer on the pan. Allow to dry in a cool place for at least 4 hours, preferably overnight, uncovered (I highly suggest overnight. They will much easier to work with)
Use a spatula to spread the marshmallows in a layer on the pan. Allow to dry in a cool place for at least 4 hours, preferably overnight, uncovered (I highly suggest overnight. They will much easier to work with)
You will know the marshmallows are drying if you lightly touch the tops an hour or two into the drying process and you start feeling a coarse, almost rough ‘skin’ on the tops of the marshmallows. If they are not forming that ‘skin’, just dust some more of the sugar/starch mixture over top.
Put the remaining the marshmallow mixture into a large bowl and dust the top of the marshmallows with some of the marshmallow mixture. Use a pizza cutter or scissors (dusted as well with the marshmallow mixture) to cut the marshmallows into any size or shape pieces that you’d like and toss the marshmallows in the sugar/starch mixture. Shake the marshmallows vigorously in a hand sifter to remove the excess powder.
The marshmallows can be made up to one week in advance and stored in an airtight container.