Ingredients

Start to finish: 45 minutes active, setting up overnight

Cooking spray
Powdered sugar
2 1/2 tablespoons unflavored gelatin
1 cup water, divided, plus 1 tablespoon
1 1/2 cups sugar
1 cup light corn syrup
1 1/4 teaspoon salt
2 teaspoons vanilla extract

Directions

Lightly coat an 8-inch square pan (at least 2 inches deep) with cooking spray. Heavily dust the pan with powdered sugar, then set aside.

In the bowl of a stand mixer, stir together the gelatin and 1/2 cup of the water. Let stand 25 minutes.

Meanwhile, in a heavy 2-quart saucepan combine the remaining 1/2 cup water, sugar, corn syrup and salt. Cook, stirring constantly, over low to medium-low heat until the sugar has dissolved.

Increase heat to medium-high and bring to a boil, stirring often. Clip a candy thermometer to side of pan.

Reduce heat to medium and boil at a moderate, steady rate, stirring frequently until the thermometer registers 244 F (236 F Utah altitude), about 15 minutes. Watch carefully to prevent mixture from boiling over. If necessary, reduce heat to medium-low.

With the stand mixer (with whisk attachment) on low to medium-low, slowly pour the hot sugar mixture into the gelatin mixture. Increase mixer to high and beat 15 minutes. Mixture should be thick, white and nearly triple in volume.

Add the vanilla extract and 1 tablespoon water, then beat until combined.

Spoon the mixture (it will be very sticky) into the prepared pan. Let stand, uncovered, overnight.

Loosen mixture from pan by running a knife around the edges. Invert onto a cutting board dusted with powdered sugar. With a large knife, cut the block of marshmallow into 1-inch squares. Dust the squares with additional powdered sugar.

Makes about 64 marshmallows.