To make square marshmallows: prepare a container for the marshmallows (see note). Lightly spray the container and then line it with two strips of parchment that fit the container to create a sling. Generously dust the container with arrowroot (or combo arrowroot and powdered sugar). Alternatively, to make traditional cylindrical marshmallows: line a sheet tray with parchment and generously dust with arrowroot. Set aside.
In a clean mixing bowl for an electric mixer with a whisk attachment, add egg whites.
In a large pot add ⅓ cup water, honey and maple syrup, in that order, being careful not to get any of the mixture on the sides of the pot. Turn the heat to medium and let the sugar mixture cook undisturbed.
Meanwhile prepare gelatin: Add ½ cup water to a small bowl. Sprinkle gelatin over the water and mix to moisten the gelatin. Let bloom (or hydrate) for at least 5 minutes. Once bloomed, add to the egg white mixture and briefly whip until the mixture is homogenized and fluffy, about 2 minutes.
When the the sugar syrup has reached 240°F, remove from the heat and let cool slightly, or until it has stopped bubbling, about 1 minute.
Then very slowly and carefully pour the sugar syrup into the egg whites bowl, hitting the side of the bowl if possible, in a thin, steady stream.
Once all of the syrup is in, increase the speed and continue to whip for 10-12 minutes, or until the mixture is thick and glossy and the mixing bowl is mostly cooled.
Add in vanilla extract and whip for one one more minute. If you are adding in any optional add-ins, add them now.
For square marshmallows: Working quickly pour mixture into the prepared container and smooth over. Dust generously with more arrowroot and let set for at least 4 hours until cutting. To cut remove from the container and cut with a pizza cutter that is greased with coconut oil. Dust again all the cut sides with more arrowroot, shaking off excess. For cylindrical marshmallows: Fill a piping bag with a large circular tip (or simply cut a piping bag) with the marshmallow mixture and pipe it in lines the length of the sheet tray until all the mixture is gone. Dust generously with arrowroot. Let set for 4 hours at room temperature. Cut with a pizza cutter that is greased with coconut oil into cyridrical shapes. Dust more with arrowroot, shaking off the excess before storing.
Let the cut marshmallows dry out for at least 6 hours before storing in an air tight container or bag. Store for up to 1 week.
The size of the pan you use to make the square marshmallows depends on how big you would like your square marshmallows. For a smaller marshmallow squares use a half sheet pan, or a 9x13 pan. For larger marshmallows use an 8"x8" or a 9"x9" pan.