Instructions

1. Combine the powdered sugar and cornstarch in a bowl. You'll use this throughout the whole process. Set aside.
2. Add the gelatin to the bowl of your stand mixer fitted with the whisk attachment. Pour 1/2 cup of the cold water over the gelatin. Let the gelatin bloom (= hydrate) while you complete the next couple steps.
3. In a heavy bottom saucepan over medium-high heat, bring the remaining 1/2 cup water, granulated sugar, corn syrup, molasses and salt to a boil, stirring to help dissolve the sugar. Attach your candy thermometer and continue to boil the sugar mixture until it reaches 240-242 degrees Fahrenheit. Remove the saucepan from the heat.
4. Turn your mixer on to low speed. Then very slowly and carefully start to stream the hot sugar mixture into the bowl. Avoid pouring the sugar mixture directly onto the moving whisk to prevent splatters. Try to keep the stream closer to the sides of the bowl. Once all the sugar mixture has been added, drape a clean kitchen towel over your mixer and increase the speed to high. Whisk on high for 8 minutes. The mixture will become thick, white and fluffy.
5. Turn your mixer back to low speed and remove the kitchen towel. Add the vanilla extract and ground spices. Return the mixer to high speed for 2 minutes.
6. Meanwhile, place a 9 X 9-inch baking pan inside a large rimmed baking sheet (this is to help keep powdered sugar from getting everywhere). Generously coat the bottom and sides of the baking pan with non-stick cooking spray. Then spoon some of the powdered sugar mixture into a fine mesh strainer or sifter and generously coat the bottom and sides of the baking pan.
7. Stop your mixer and immediately transfer the marshmallow mixture to your prepared baking pan using a spatula sprayed with non-stick cooking spray. The marshmallow mixture should easily spread to evenly fill the pan. It will, however, become thick and sticky over time. So work quickly to get it all from the bowl of your mixer to your baking pan before that happens.
8. Generously cover the top of the marshmallow with some of the powdered sugar mixture. Then set it aside to let the marshmallow dry and set at room temperature, uncovered, for at least 6 hours or up to overnight (overnight is highly recommended). Save the remaining powdered sugar mixture.
9. Once dry and set, dust the rimmed baking sheet with some of the powdered sugar mixture. Then coat your fingers with some of the powdered sugar mixture and use them to slowly pry the edges of the marshmallow away from the sides of the baking pan. Once the edges have been loosened, the marshmallow should easily lift/flip out of the baking pan as one large block. Place the marshmallow top side-down onto the rimmed baking sheet. Coat the now exposed bottom surface of the marshmallow with some of the powdered sugar mixture. Let the marshmallow dry for an additional 2-4 hours at room temperature.
10. Using a very sharp knife dusted with some of the powdered sugar mixture, slice the marshmallow into 16 squares. Toss the squares in the remaining powdered sugar mixture to coat all sides.
11. Slowly melt the chopped chocolate in a small saucepan set over medium heat, stirring continuously until smooth. Remove the saucepan from the heat and let the chocolate cool for about 3-5 minutes. Shake off any excess powdered sugar from the marshmallows. Then spoon an approximately tablespoon amount of the melted chocolate in the center of each marshmallow. Place a piece of crystalized ginger in the center of the chocolate while it’s still wet. 
12. Once the chocolate has set, the marshmallows can be transferred and stored in an airtight container at room temperature for 2-3 weeks, although they are best when eaten within 1 week of being made.