Line a 9″x9″ baking pan with saran wrap. Sprinkle liberally with powdered sugar. Set aside.
In a standing mixer with a whisk attachment, pour 1/2 cup water and gelatin into bowl. Mix and allow for gelatin to “bloom” for at least 5 minutes.
Combine sugar, corn syrup, salt, powdered and fresh gingers, and remaining 1/2 cup water in a medium saucepan. Attach a candy thermometer to the side of the bowl. Heat over medium heat, stirring with a heat-safe spatula. Once the sugar is dissolved, increase the heat and boil without stirring until the mixture reaches 240°F, about 8 minutes. Immediately remove from heat.
Turn the standing mixer to low speed and slowly pour the sugar mixture into the bowl with the gelatin mixture. Once added, increase speed to high and whip for approximately 15 minutes, until the mixture becomes very thick and stiff. Add the vanilla extract in the last minute of whipping.
Pour mixture into prepared baking pan, smoothing the top with a spatula. Knock the pan on a counter to release any air bubbles from within the mixture. Sprinkle top with powdered sugar and allow to cool at room temperature for at least 4 hours.
Once cooled, remove the marshmallow block from the pan. Toss together the 1/4 cup of powdered sugar and corn starch and spread out in a shallow bowl. Cut the marshmallow block into 1.5″x1″ rectangles. Toss each rectangle into the powdered sugar mixture to coat. Set on a cookie rack.
Melt the chocolate in a microwave-safe bowl in 30 second increments, stirring in between each time. Dip each marshmallow half-way into the melted chocolate, shake to remove excess chocolate, and set back on the cookie rack. Allow to cool for ~3 minutes before sprinkling with candied ginger pieces. Allow for chocolate to harden completely before serving.