Home Made Vanilla Marshmallows

12 sheets of gelatin (or .75 ounces of powdered gelatin)
2 cups sugar
1 cup light corn syrup
2 teaspoons vanilla extract
1/8 teaspoon salt
1/2 cup sifted powdered sugar, plus more for dusting

Grease a 9 x 13 x 2 inch pan with vegetable shortening. I used a sandwich baggie as a glove. Be sure to coat the pan well and don't miss any of the edges or sides. Set aside.
If you are using the gelatin sheets, place them in a medium or large heatproof bowl. Fill bowl with very cold water and set aside. Add a few ice cubes to keep the water cold.

If you are using powdered gelatin, place about 1 cup of ice cold water in a medium sized heatproof bowl. Lightly sprinkle the gelatin over the surface of the water. Do this slowly and don't just dump it in as it could cause the gelatin to clump.
In a medium saucepan, gently stir together the sugar, 1/2 cup of the corn syrup, and 1/2 cup water. Be careful not to splash the mixture around as it will harden up on the sides of your pan. Put the saucepan over medium-high heat and clip a candy thermometer on the side of the pan.
Fill a medium size saucepan half way with water and place on the stove over medium-high heat (aka a double broiler).

Put the remaining 1/2 cup corn syrup in a bowl of a stand up mixer fitted with the whisk attachment and set aside.

Return to the saucepan of water and check the temperature. When the temperature reaches 220 degrees F drain the water from the bowl of gelatin and gives the sheets of gelatin a quick wringing out.

If you are using the powdered gelatin, pout the entire bowl (ice water and gelatin) through a strainer with very very tiny holes. Don't use a pasta or vegetable strainer otherwise you'll lose the gelatin down the drain.
Place the bowl of gelatin over the saucepan on simmering water and stir the gelatin with a heat safe spatula until it is completely melted. Remove the bowl from the pan.
Turn the mixer on low speed and slowly pour the melted gelatin into the corn syrup. Keep mixer on low.

Bring the sugar mixture to the soft ball stage on the candy thermometer (235-240 degrees F), then remove from heat. Remove the thermometer from the pan. Turn up the mixer to medium for 1 minute, then slowly pour the sugar mixture into the gelatin mixture. When all of the sugar has been added, turn up the mixer to medium-high and beat for about 5 minutes.

The marshmallow mixture will finally start to look like marshmallow and become white and fluffy.
Add the vanilla and salt and turn the mixer up to its highest speed for another minute.  
Working very quickly, pour the marshmallow into the prepared pan. Use an offset spatula to spread the mixture evenly. Sprinkle with a bit of powdered sugar and let sit for about 6 hours.
Lightly dust your kitchen counter with powdered sugar. Use a knife to loosen the marshmallow from the edges of the pan and use your hands to pull the marshmallow (it will come out in one big piece) out of the pan onto your counter.
Place 1/2 cup of the powdered sugar into a bowl. Use a chef's knife to cut the marshmallows into a 6 x 8 grid. Roll each marshmallow in the powdered sugar. I found that the best way to cut was to really chop down hard with a lot of powdered sugar sprinkled on top. When I say a lot, I mean it. You can't over-do it with the powdered sugar while you're cutting as it won't absorb into the marshmallow. If you feel your knife sticking, sprinkle powdered sugar on top of it (even if it's stuck, this will help it loose).
Store in an air-tight container for up to 1 week.
Marshmallow recipe from the cookbook Baked: New Frontiers in Baking by Matt Lewis and Renato Poliafito