Next time I will use a square smaller pan to make the marshmallows thicker and will add a second egg white, which I will fold in more carefully to try to get more of a "jet-puffed" texture. I don't want them to be quite as light as store bought, but lighter than they were this time.
About 1 cup confectioners’ sugar
3 1/2 envelopes (2 tablespoons plus 2 1/2 teaspoons) unflavored gelatin
1 cup cold water, divided
2 cups granulated sugar (cane sugar worked just fine)
1/2 cup light corn syrup
1/4 teaspoon salt
2 large egg whites or reconstituted powdered egg whites
1 tablespoon vanilla
Oil glass pan, then sprinkle with powdered sugar as you would flower a pan.
In Kitchenaid bowl sprinkle gelatin over 1/2 cup cold water. Set aside for it to soften and create a kind of jell, the gelatin will absorb all of the water.
To test the stage drop a small amount of the boiling sugar into cold water, if it forms a soft ball when you pull it out you have reached the soft ball stage. If it forms a hard ball, you have heated it too much.
Stir sugar mixture into gelatin. Beat until it has tripled in volume. In separate bowl with clean beaters beat egg whites to stiff peaks. Mix into sugar mixture.
Poor into pan. Sift powdered sugar over the marshmallows.
Let this dry for 3 to 24 hours. Run a butter knife around the edge and turn out onto cutting board. Use a oiled pizza cutter to slice into the appropriate sized squares.
Roll each marshmallow in powdered sugar, this will make the sides less sticky.
Store in air tight container. Be warned that the powdered sugar will get everywhere in your kitchen. Hopefully my next round will work out right.