Prep a 9" square pan. I grease the entire pan with room-temp unsalted butter, line the bottom with parchment paper, then grease over the paper as well.
In a medium sauce pot, combine the granulated caramel, corn syrup, and water. Stir to evenly distribute ingredients and scrape with a rubber spatula to ensure no sugar is stuck to the bottom of the pot.
Cook over med-high heat until it starts to boil.
Once it begins to boil, lower heat to medium, cover with a lid for 2 minutes. DO NOT remove the lid during the 2 minutes. No peeking!
After 2 minutes, remove the lid and place a thermometer inside the pot. Take care that it's not just resting on the bottom of the pot because it will read higher. Cook the caramel mixture until it reads between 242-245℉.
Bloom your gelatin while you're waiting for the right temperature. Place the gelatin in the bowl of your stand mixer and add ½ cup of water to it. Give it a light stir, then let it sit for 10 minutes to bloom.
When your caramel mixture has reached at least 242℉, take it off of the heat and wait for the bubbles to subside.
Once the gelatin has finished blooming for 10 minutes, very slowly pour in the caramel mixture on one side of the stand mixer bowl while it whisks at medium to high speed (adding the mix to the gelatin all at once will scorch it!).
When all of the caramel is added to the gelatin, increase to high speed whisking. Add in the salt and vanilla bean paste at this time. After approximately 5 minutes, the mixture should look very light in color and be at least doubled in size. Feel free to add a few more minutes if needed.
Once the caramel marshmallow mixture is sticky and fluffy, grease a rubber spatula generously with unsalted butter. Scoop the caramel marshmallow mixture into your prepped pan and flatten it evenly until it touches all edges and corners.
Dust the top of the marshmallows with powdered sugar and sit at room temperature for about 5 hours. Feel free to cover loosely with cling wrap if needed.
Once at least 5 hours has passed, generously grease a knife with unsalted butter. Use this to cut the marshmallow into 16 equal sizes (roughly 2.25" squared). You can cut them as big or as small as you like, but this is definitely my preference as they fit into standard mugs of cocoa easily.
Once cut, with a little more powdered sugar, I like to rotate each marshmallow so that each edge is dusted. I store them in a Stasher, and this step helps prevent them from sticking to each other.