Modified from Martha Stewart
2 envelopes unflavored gelatin
1 1/2 cups sugar
2/3 cup light corn syrup
1/8 tsp salt
1 tsp homemade bourbon vanilla
vegetable oil cooking spray
Coat a 9 x 13-inch baking pan with cooking spray, line with parchment paper (leave an overhang of parchment to use as "handles" to help remove the marshmallows later). Pour 1/3 cup cold water into the bowl of an electric mixer. Sprinkle with gelatin and let the mixture soften, about 5 minutes.
Place sugar, corn syrup, salt and 1/3 cup water in a saucepan. Whisk together to combine. Cover, bring to a boil. Remove lid, cook, swirling occasionally, until the syrup reaches 238ºF, about 5 minutes.
With the mixer on low speed, whisk the gelatin mixture and slowly pour in the syrup in a steady stream down the side of the bowl. Gradually raise the speed up to high, beat until the mixture is thick, white, and almost tripled in size, about 12 minutes. Add vanilla and beat about 30 seconds, until combined.
Pour the mixture into prepared baking sheet and smooth with a spatula. Let stand at room temperature, uncovered for 3 hours or overnight.
Cut (with a pizza cutter sprayed with non-stick spray), roll each marshmallow in powdered sugar and enjoy! Store in an airtight container for up to a week.
*note: for thicker marshmallows, use a 9 x 9-inch pan, or double the recipe and use a 12 x 17-inch.*