For Marshmallows• ½ cup ice water (118ml)• 3 packets gelatin (0.75 oz)• 2 cups granulated sugar (400g)• 1 cup light corn syrup¹ (236ml)• ½ cup water any temperature (118ml)• ¼ teaspoon table salt• 1 Tablespoon vanilla extract• Additional powdered sugar as needed
Prepare a 13×9” (33x23cm) pan by thoroughly greasing the sides and bottom with vegetable shortening (I use Crisco) or a thin layer of vegetable oil. Grease a rubber spatula as well.
In a medium-sized pot, combine sugar, corn syrup, remaining ½ cup (118ml) water and salt. Turn stovetop to medium and cook, stirring frequently, until sugar is dissolved.
Continue to stir until mixture comes to a boil, then attach a candy thermometer to the pot and continue to cook without stirring until mixture reaches 242F (115C).
Remove syrup from heat and turn stand mixer speed to low. With mixer on low speed, gradually drizzle the hot syrup into the gelatin mixture in a steady stream.