4 envelopes unflavored gelatin

3 cups granulated sugar

1 1/4 cups light corn syrup

1/4 teaspoon salt

2 teaspoons pure vanilla extract

1 1/2 cups confectioners' sugar

1 1/2 cups water divided


Spray 9x13 lightly with cooking spray

line the pan with parchment coming up the sides (at least 2 inches) on each end.

Spray the parchment lightly with cooking spray.

Put granulated sugar, corn syrup, salt, and 3/4 cup water into a medium saucepan. Bring to a boil over high heat, stirring to dissolve sugar. Without stirring, continue to cook syrup until mixture registers 238° on a candy thermometer, between 7-9 minutes.
While the syrup is boiling pour 3/4 cup water into bowl of stand mixer.  Sprinkle the gelatin on the water and let it sit 5 minutes so gelatin softens.
When sugar syrup comes to a boil slowly pour the  hot syrup into the gelatin.  With the whisk attachment on the mixer beat on high for 12 minutes until marshmallow is very stiff.
Add vanilla and beat for 1 more minute.
Pour marshmallow into prepared pan and spread with a spatula.  It will be VERY sticky!
Let sit for at least 3 hours uncovered.
When you're ready sift 1 cup powdered sugar onto work space.
Remove the marshmallow from pan onto sugared counter.
Using a VERY SHARP knife cut the marshmallow into squares.
(You might find it helpful to spray knife with cooking spray)
For plain marshmallows sift remaining 1/2 cup powdered sugar into a bowl and coat each cut marshmallow with sugar.
Will store airtight for up to a week.