Oil bottom and sides of a 13- by 9- by 2-inch rectangular metal baking pan and dust bottom and sides with some confectioners' sugar.
powdered sugar
In bowl of a standing electric mixer or in a large bowl sprinkle gelatin over cold water and let stand to soften.
2 tbsp unflavored gelatin, 1/2 cup cold water
In a 3-quart heavy saucepan cook granulated sugar, corn syrup, hot water, and salt over low heat, stirring with a wooden spoon, until sugar is dissolved. Increase heat to moderate and boil mixture, without stirring, until a candy or digital thermometer registers 240°F., about 12 minutes.
2 cups granulated sugar, 1/2 cup light corn syrup, 1/2 cup warm water, 1/4 tsp Salt
Remove pan from heat and pour sugar mixture over gelatine mixture, stirring until gelatine is dissolved.
With standing or a hand-held electric mixer beat mixture on high speed until white, thick, and nearly tripled in volume, about 6 minutes if using standing mixer or about 10 minutes if using hand-held mixer.
In a large bowl with beat the egg whites until they just hold stiff peaks. Beat whites and vanilla into sugar mixture until just combined.
2 large eggs, 1 tsp vanilla
Pour mixture into baking pan and sift 1/4 cup confectioners sugar evenly over top. Chill marshmallow, uncovered, until firm, at least 3 hours, and up to 1 day.
Run a thin knife around edges of pan and invert pan onto a large cutting board. Lifting up 1 corner of inverted pan, with fingers loosen marshmallow and let drop onto cutting board. With a large knife trim edges of marshmallow and cut marshmallow into roughly 1-inch cubes. temperature 1 week.
Sift remaining confectioners' sugar into a large bowl and add marshmallows in batches, tossing to evenly coat. Marshmallows keep in an airtight container in a cool room
Notes
Who doesn't love marshmallows. In a hot chocolate, over a bonfire, as a treat are all lovely ways to consume marshmallows.