Line a baking sheet or dish with parchment paper. Stir the gelatin into 1/3 cup water.
Place the granulated sugar, 1/3 cup water and corn syrup in a small saucepan over medium-high heat. Bring to a boil, stirring, and cook until the sugar dissolves and the temperature reaches 240°F. Carefully pour the sugar mixture into the gelatin mixture, stirring constantly. Let sit for 5 minutes.
Using an electric mixer, whip the egg whites until soft peaks form. With the mixer on medium-low speed, pour the sugar-gelatin mixture into the egg whites in a slow, steady stream. Continue whipping until stiff peaks form. Pour the mixture into 8-by-8-inch baking sheet or dish and refrigerate until stiffened, about 3 hours.
Turn the marshmallow out onto a surface sprinkled with powdered sugar; peel off the parchment. Cut into 4 cubes and insert a bamboo stick into each.