Lightly butter a 9x13 pan and line it with a sheet of parchment paper, leaving long ends for easy lifting later. Dust the lined pan with powdered sugar.

In the bowl of a stand mixer fitted with the balloon whisk attachment, add the cold water. Sprinkle the powdered gelatin over the water and let it sit to bloom.

In a relatively deep saucepan, pour in the maple syrup. Bring it to a boil over medium heat and cook until it reaches the soft ball stage, or 235°F on a candy thermometer.

Once the syrup reaches the correct temperature, remove the pan from the heat. Turn the mixer on low to combine the gelatin and water mixture, then slowly drizzle in the hot syrup while the mixer is running.

After all the syrup has been incorporated, increase the mixer speed to high and beat until the mixture becomes thick, glossy, and holds stiff peaks. Add a pinch of salt during this process.

Immediately spread the viscous mixture into the prepared pan, using an offset spatula to spread it evenly.

Allow the marshmallows to set at room temperature for several hours, or ideally overnight, to firm up.

To remove the marshmallows from the pan, use the parchment paper as a sling, inverting the marshmallow slab onto a surface dusted with sifted confectioner's sugar. Gently peel off the parchment.

Dust the surface of the marshmallows with additional confectioner’s sugar. Use a long, sharp knife to slice them into strips and then cut those strips into cubes, dusting all exposed edges with confectioner’s sugar to prevent sticking.

Store the marshmallows in an airtight container for up to two weeks.