In the bowl of your stand mixer, combine 1/2 cup of the water with the gelatin. Just pour the gelatin over the top of the water and let that sit while you work with the sugar.

In a medium sized pot, combine the remaining 1/2 cup water, espresso powder, sugar, and corn syrup over medium heat. Stir until dissolved. Turn the heat up to medium and allow the mixture to reach 240°F (also called "soft ball"). Watch that the mixture doesn't boil over from the pan. Just give it a stir if it seems too close. Once the mixture reaches the desired temperature, remove from heat.

Turn your mixer (with the gelatin water) on low. If your mixer has a splash guard, here's a good time to use it. Carefully pour the hot sugar mixture into the mixer while it's running. Be careful when working with hot sugar! Now pour in the vanilla extract. Turn the speed up to medium/high and beat for about 5-6 minutes until the batter looks fluffy, like marshmallow cream.

In an 8×8 square pan, spray on a thin coat of nonstick cooking spray. Then sprinkle generously with powdered sugar and a little more espresso powder so you'll get some pretty flakes in your marshmallows. You could use a larger, rectangle baking pan for a thinner marshmallow. Totally up to you! I like to make mine thick and then cut them into small cubes or shapes. So that's why I use a square pan. Pour in the marshmallow cream. Sprinkle on some powdered sugar and espresso powder. Then cover and allow to set for at least three hours, or overnight.

The next day gently peel the marshmallows out of the pan and place on a cutting board. Use a pizza cutter to slice into squares. Or you can use cookie cutters to make shapes! Store in an airtight container for up to two weeks.