Packaged marshmallows can not compare with these heavenly sweet pillows. Try using different extracts in place of vanilla, such as almond, lemon, or orange.
Spray a 13x9-inch baking pan with nonstick cooking spray. Line the bottom of the pan with parchment or wax paper. Sift half of the confectioners’ sugar over the parchment paper. Set aside.
In the bowl of a stand mixer, combine ½ cup of cold water with the gelatin. (If using an electric hand mixer, place ½ cup of cold water and gelatin in a large bowl.) Allow the gelatin to “bloom” and soften, about 15 minutes.
In a medium saucepan, combine the remaining ½ cup of cold water, sugar, corn syrup, and salt. Stirring, bring to a boil over medium heat. Increase heat to high. Do not stir. Cook until it reaches 240°F on a candy thermometer.
Remove the saucepan from the heat. Set the mixer on its lowest speed and slowly pour the corn syrup mixture into the softened gelatin. Try not to get any of the syrup on the beater(s). Gradually increase the mixer speed until you reach the highest speed. Beat until the mixture has tripled in volume and is very thick, glossy, and stiff, about 10 minutes. (This will take longer if using an electric hand mixer.) During the last minute of mixing, slowly stream in the vanilla.
Scrape the mixture into the prepared pan, spreading quickly. You may need to wet a rubber spatula with water and use it to spread the mixture. Sift the remaining confectioners’ sugar over the top. Set aside for 12 hours or overnight.
Dip a cookie cutter in confectioners’ sugar and cut out marshmallow shapes. These may be stored at room temperature in an airtight container for up to 1 month.