Place the gelatin and 1/2 cup of COLD peach syrup into the bowl of a stand mixer with whisk attachment.
In a small saucepan remaining peach syrup, granulated sugar, and corn syrup. Place over medium high heat, cover and allow to cook for 3 minutes. Uncover, and continue to cook until the mixture reaches 240 degrees F, approximately 7 to 8 minutes. Once the mixture reaches this temperature, immediately remove from the heat.
Turn the mixer on low speed and, while running, slowly pour the sugar syrup down the side of the bowl into the gelatin mixture. Once you have added all of the syrup, increase the speed to high. Continue to whip until the mixture becomes very thick and the mixing bowl is cool to touch.
Lightly spray a 13 by 9-inch baking pan with nonstick cooking spray. Cover the pan with sifted powdered sugar.
When ready, pour the mixture into the prepared pan. Dust the top with more sifted powdered sugar. Refrigerate marshmallows uncovered for several hours.
Once the marshmallows have set, gently remove them from the pan using your hands and coat with more sifted powdered sugar. Cut the marshmallows into squares using a pizza cutter, and toss in sugar/spice mixture to coat.
Store in an airtight container with remaining sugar and spice mixture for up to 3 weeks.