Add 1/2 cup cold water and gelatin to a medium saucepan. Whisk together, then let it sit for 5–10 minutes to bloom.
Turn the heat to medium and warm the mixture until it becomes liquid. Add cane sugar (or maple syrup) and salt, whisking until everything is fully dissolved and smooth.
Pour the mixture into a stand mixer fitted with the whisk attachment. Start on low and gradually increase the speed as it thickens. Whip for 8–10 minutes until it becomes thick, fluffy, and glossy with soft peaks. During the last minute, add vanilla.
Quickly pour the marshmallow mixture into a greased or parchment-lined pan and smooth the top. Place in the fridge for several hours, until firm.
Once set, dust the top with powdered sugar. Remove from the pan, dust the sides, and cut into squares or fun shapes. Enjoy!