Start by adding the gelatin to the ¼ C cold water and mix to form a paste. Let that sit for about 10 minutes and move onto step 2.
In a large saucepan over low heat, add the granulated sugar and ¾ C water. Stir to dissolve, and keep stirring.
Once the gelatin has set for 10 minutes, add it to the water/sugar mixture and keep stirring until it’s fully dissolved. You will start to see a lot of bubbles.
Raise the heat to medium/high and keep stirring.
Once the mixture starts to boil, stop stirring and turn down the heat slightly until you start to see bits of caramel bubble up. Once you see these bits and the mixture starts to turn a caramel color, turn down the heat to maintain a steady, slow boil. Let it bubble for about 15 minutes and refuse the urge to stir it!
Add the mixture to a large bowl or mixer, along with the vanilla and cinnamon. Beat on medium speed until it turns into a very light tan color. It should be opaque and thick, like marshmallow fluff.
Spray a 9×9 pan with the baking spray and dust it with a mixture of the cornstarch and powdered sugar. I use a sifter to evenly distribute it and to avoid lumps.
Add the marshmallow mixture and be sure to lick your spatula because it’s freaking delicious. It is hard to spread it out evenly, but after a few minutes it will settle pretty flat.
Let the marshmallows set completely – about an hour and a half.
Once fully set, remove from the pan and cut into squares. My favorite tool to do this is a bench scraper but a pizza cutter or even cookie cutters work well, too. Dust the squares with the remaining cornstarch and powdered sugar.