In the bowl of a stand mixer fitted with a whisk attachment, add 113g (½ cup) of water and sprinkle the gelatin on top in an even layer. Set aside to bloom.
In a large saucepan, combine the other 113g (½ cup) of water, granulated sugar, light corn syrup, and salt.
Heat the saucepan over medium heat, stirring frequently until the sugar dissolves. Raise the heat to medium-high, and without stirring, bring it to 240 degrees F.
While the mixer is on low speed, slowly drizzle the hot sugar over the gelatin.
Once all of the hot sugar is poured in, increase the mixer speed to high and mix until thick and cool (about 100 degrees F). Add the vanilla paste while it is mixing.
Pour the marshmallow mixture on top of the ganache layer. Tap the pan on the counter a few times to release any air bubbles.
Sprinkle a small amount of powdered sugar on top, and cover with plastic wrap. Allow to set at room temperature for at least four hours or overnight.
Once set, use a sharp, buttered knife to cut the bars into 16 squares. Use a kitchen torch to toast the tops of the marshmallows. Enjoy!