- 3 packages unflavored gelatin
- 1 cup ice cold water, divided
- 1 1/2 cups granulated sugar
- 1 cup light corn syrup
- 1/4 tsp salt
- 1 tsp vanilla extract
- 1/4 cup powdered sugar
- 1/4 cup cornstarch
- butter, room temperature, for pan
- In the bowl of a stand mixer combine 1/2 cup cold water with the 3 packages of gelatin. Let it set up for 30 minutes.
- While your gelatin is setting, prepare a 9×13 dish by buttering it liberally. In a small bowl combine the powdered sugar and cornstarch, and coat the buttered dish with the mixture. Save the extra powder mixture for later.
- Combine the remaining water, granulated sugar, corn syrup, and salt together in a sauce pan. Cover, and cook over medium-high heat for 3-4 minutes. Remove the lid and attach a candy thermometer, continuing to cook without stirring. Cook until the temperature reaches 240 degrees F, then remove from heat immediately.
- With the gelatin in the mixing bowl, turn the mixer (fitted with the whisk attachment) onto low speed while you slowly pour the hot sugar mixture into the bowl. Once it is all in, turn the mixer up to high speed at let it run for 12-15 minutes. The mixture should greatly increase in size, turn white, and cool to lukewarm. Add the vanilla in the last minute of mixing.
- With a buttered spatula, pour the mixture into the prepared pan and flatten as smoothly as possible. Pour more of the powder mixture on top and spread it to cover all exposed marshmallow. Let the marshmallow set up for at least 4 hours, and up to overnight, uncovered.
- When ready, turn out onto a kitchen towel lightly coated in powdered sugar. Cut to your desired shape/size, liberally coating in the powder mixture as needed.