Prepare an 8x8 or 9x9 square pan with parchment paper. I like to cut the parchment downward in the corners of my pan to make it lay nicer.
In the bowl of your mixer, gently combine the gelatin powder and ½ cup water. Set aside to bloom. Ensure you have the whisk attachment ready.
3 Tbl gelatin powder, ½ cup water
In a medium-large saucepan, combine the honey, ¼ cup water, and pinch of salt. Bring to a boil, and allow to remain at a rolling boil for 2-3 minutes. If you have a temperature probe, temp to see that the temperature has reached 240℉, or the "soft ball" stage of candy making. Then turn off the heat.
1 cup honey, ¼ cup water, 1 pinch salt
Quickly bring the hot honey mixture over to your mixer, and turn it on low. Slowly pour a steady stream of the honey mixture into the gelatin, until it's all combined. Ensure you're going slowly, and use a splash shield if you have one. Molten sugar splatter is not a fun time. Gradually increase the speed until you're able to safely beat the marshmallows on medium-high.
While the marshmallows are mixing, add the vanilla. Then continue to beat until it reaches the consistency of a thick cream, like marshmallow fluff. It should be thick enough that when you pull the whisk out of the mixture, it will leave drip ribbons on the top that slowly sink back in.
1 teaspoon vanilla
Once it's thick, pour the marshmallow cream into the parchment-lined pan. It will begin to get sticky and solid quickly, so don't let it sit in the bowl for more than a minute or so. Set aside, and allow to cool at room temperature for at least 4 hours. After they're completely solid, lift the marshmallow slab out of the pan using the parchment paper. Then use a hot knife (run under hot water for a moment) or cookie cutters to cut out your marshmallows. You can then coat them lightly in the powdered sugar and cornstarch mixture to keep them from being unreasonably sticky. ¼ cup powdered sugar + 1 Tbl cornstarch
You can store the marshmallows in an airtight container for up to 2 months, or freeze them for 6-8 months.