Oil 9x13 pan
Sprinkle gelatin over 1/2 cup of cold water and vanilla extract in a large bowl
Place 1/2 cup cold water and remaining marshmallow ingredients into a large saucepan
Over medium heat, stir saucepan ingredients until mixture is bubbling and clear
Continue to heat, without stirring, until mixture reaches 240 degree F
Remove from hear and pout hot mixture over the gelatin
Using a stand or hand mixer, beat for approximately 10 minutes o high, until you see strings of marshmallow pulling away from the sides
Spread marshmallow evenly in 9x13 pan
Let marshmallow sit for 4_nhours
Sift powdered sugar and cornstarch together
Dust powdered sugar mixture over the top of the mash mallows.
Cut marshmallow to desired size
Remove marshmallows from pan, dust all sides with powdered mixture
Shake excess dusting off
Store in airtight bag or container