Line a 9×13 inch baking dish with parchment paper and evenly and generously sprinkle with arrowroot starch.* Grease a spatula with coconut oil or palm shortening.
Add 1 cup cold water to a bowl and evenly sprinkle gelatin on top to allow it to bloom (about 5 minutes).
In a small saucepan over medium heat, whisk together maple syrup, remaining ¼ cup water, sea salt and vanilla. Bring to a vigorous boil and allow to boil at least 60 seconds so the mixture is very hot.**
In the bowl of a stand mixer with a whisk attachment or in a large bowl with an electric hand mixer, add the bloomed gelatin mixture and whisk on high speed.
Slowly pour in the boiling hot maple syrup mixture against the side of the bowl. Beat on high for 3.5-5 minutes, until soft peaks form. The marshmallow mixture should be light and fluffy, and should triple in volume.***
Quickly pour the mixture into the prepared pan. Use the greased spatula to evenly spread the mixture and smooth the top.
Use a sifter or fine meshed sieve to dust the top with arrowroot starch.
Cover the dish with plastic wrap and allow it to set on the countertop for a minimum of 6 hours or overnight.
Lightly grease a sharp knife with coconut oil or palm shortening and slice the marshmallows into squares. Toss with additional starch if necessary.****
