Line a baking pan with parchment paper (optional), and sprinkle the parchment (or pan) with a layer of the arrowroot and powdered sugar mixture (or just arrowroot).
In a large bowl, sprinkle the gelatin evenly over 1/2 cup of water. Don’t stir, just let it rest.
In a medium-size saucepan, stir the maple syrup, 1/2 cup of water, and salt. Add a candy thermometer to the edge of the pan. Turn the heat up to high and bring the mixture to a boil, then reduce to medium heat. Heat the maple syrup mixture until it reaches 238F (around soft candy stage).
With a hand mixer on low speed, pour the maple mixture slowly into the gelatin. Add the vanilla extract. Increase the speed to medium/high and beat the mixture for about 10 minutes or until silky, smooth, white, and fluffy (should look like marshmallow fluff). It's really easy to over-beat the mixture when using a stand mixer, which is why I recommend using a hand mixer. If you're using a stand mixer, don't walk away from the mixture. Pay close attention to the change in texture. You might need to reduce the beating time for a stand mixer as well.
Once ready, the marshmallow mixture should be silky, smooth, fluffy, and white (see photos above). You can spoon a small amount on a plate to see if it maintains shape.
Add the marshmallow mixture to the prepared baking pan. Sprinkle the marshmallows with more of the arrowroot and sugar mixture (or just arrowroot) to evenly coat the top. Spread the mixture evenly over the marshmallows with your hands or spatula, if needed.
Let the marshmallows rest overnight or up to 24 hours (particularly for a very humid climate). It’s best to let the marshmallows rest uncovered so they can dry out. I’ve been successful with just a few hours of resting time when the humidity is low. You can test for readiness by cutting a small piece. The individual piece should be dry. If you cut the marshmallows too early (they still need more drying time), keep the cut marshmallows in the baking pan until fully dry.
Store the marshmallows in an air-tight container or bag. I’ve found they are best stored in the freezer (a cool, dry place). They won’t freeze to a solid due to the gelatin, so they’re always ready to enjoy. The marshmallows should keep in the freezer for up to 3 months, or on the counter (or fridge) for a couple of weeks.
Notes
*Arrowroot Starch and Powdered Sugar: If you want super sweet marshmallows, go with the powdered sugar and arrowroot mixture. At this point, I just use arrowroot flour starch and skip the powdered sugar. I find the marshmallows are plenty sweet with just the maple syrup. If you don't want to use arrowroot, or can't find it, use organic cornstarch.I know, a candy thermometer is a speciality tool, and you'll probably never use this tool again (if you're like me). Well, except to make more marshmallows. This thermometer is very important. Without one, it's difficult to know when the maple syrup mixture has reached the correct temperature.Homemade marshmallows melt much faster than store-bought marshmallows. We have made s'mores with these marshmallows, but they can be finicky and melt quickly over a very hot flame. It's best to toast them for a short period of time over low heat. They will also slowly melt in a hot drink. These are also delicious to eat as a candy treat.