Lightly grease a 9-inch square pan and generously dust the bottom and sides with powdered sugar.

In a medium bowl, sift together cornstarch and powdered sugar (or whisk thoroughly), and set aside.

Pour the water in a large mixing bowl.

Sprinkle the gelatin over the water, and allow to stand for 10 minutes, or while following the next steps.

Meanwhile, in a large saucepan over medium-high heat, combine granulated sugar and corn syrup.

Cook until granulated sugar is dissolved, about 6 minutes.

With the mixer on the lowest setting, very slowly drizzle the sugar mixture into the gelatin mixture. It's obviously extremely hot, so you want to make sure the sugar mixture doesn't splash.

Gradually increase the mixer speed to medium for 1 minutes, or until the mixture begins to thicken.

Then increase the speed to high, and let it beat until the mixture turns very thick, white, and fluffy, about 10 minutes.

Add the vanilla and mix until incorporated.

Add the malted milk powder and mix until incorporated.

Spoon the marshmallow mixture into the prepared pan and spread evenly.

Drizzle the caramel sauce over the marshmallow mixture, and use a knife to swirl it.

Allow marshmallow to set for at least 2 hours, or overnight.

Cut into pieces with a wet knife, and toss in the cornstarch/powdered sugar mixture.