- Whisk together cornstarch and confectioners' sugar.
- Lightly oil a 13"x9"x2" pan and dust with some of the cornstarch mixture, reserving the remainder.
- In the bowl of a stand mixer, sprinkle gelatin over 1/2 cup cold water and leave it to soften while you make the syrup.
- In a medium saucepan, whisk together remaining 1/2 cup of cold water, sugar, and corn syrup. Bring to a boil over medium-high heat without stirring and continue cooking undisturbed until syrup registers 240F (115C) on a candy thermometer, about 7-10 minutes.
- Fit stand mixer with whisk attachment and turn the machine on to low speed. Slowly add hot syrup to the gelatin mixture, pouring syrup in a thin stream. Beat mixture on medium-high until it is marshmallowy and cool to the touch and has nearly tripled in volume. Add the salt and vanilla, mixing on low speed until fully incorporated.
- Use a rubber spatula lightly coated with vegetabl oil or cooking spray to spread the marshmallow evenly in the prepared pan. Dust the top with cornstarch mixture and make sure it's completely coated and doesn't have any sticky spots. (Reserve remaining cornstarch mixture.) Let the marshmallow set overnight before cutting.
- Invert pan onto large cutting board. Lift up one corner of the inverted pan and use fingers to ease marshmallow out of pan onto cutting board. Use a large knife to trim marshmallow edges straight and cut into roughly 1" cubes. (An oiled pizza cutter can work too.)
- Sift remaining cornstarch mixture into now-empty baking pan and roll marshmallows through it, coating all sides and shaking off excess. Transfer to airtight container and keep at room temperature up to 1 week or freeze for 1 month.
Homemade marshmallows! What more needs to be said?! Except that they seem to keep VERY well - longer than the recipe's recommended time. They are beautifully silky and soft and toast up fabulously.
Part of the reason I started baking was because I like my goodies to be less obviously sweet - I want to taste the flavor, not just the sugar. So most of these recipes will have the sugar dialed down.