Dust the bottom of your 9x9 pan with the powdered sugar.
Add cold water and gelatin to a bowl and let it bloom.
On the stove, add the maple syrup to the pot and begin to heat it.Once it reaches 240º, add the salt and vanilla extract. (Be quick but careful. You don't want to spill it, but you also don't want it to get thick and hard to work with.) Slowly add it to your bowl with the bloomed gelatin while mixing with your mixer. If using a stand mixer, turn the mixer on slow while you slowly pour the syrup into the bowl.
When all of the syrup is added and incorporated a little, turn the mixer on high.
Once the mixture comes to soft peaks, turn the mixer off and add the mixture to your dusted 9x9 pan and smooth it out.
Once smooth, dust powdered sugar on top while it sets.
Once set, cut the marshmallows into one inch squares and enjoy!