Weigh out the ingredients
You'll need sugar, light corn syrup, unflavored gelatin, salt, water, vanilla, and powdered sugar.
Prepare square pan
Line a 9" square pan with parchment paper. Grease the parchment paper with softened butter, then generously sprinkle with powdered sugar.
Add water to the bowl of a stand mixer. Sprinkle the gelatin in an even layer, and set aside to bloom. Meanwhile, heat the remaining ingredients in a saucepan to 240 degrees F.
Bloom the gelatin
Pour the hot sugar into the bloomed gelatin and whisk on high speed until thick & cool. Pour into the prepared pan, and allow to set for at least four hours.
Whisk & Set
Cut the marshmallows into mini squares then toss in a bowl with powdered sugar. Enjoy with hot cocoa or as s'mores!