Combine the powdered sugar, cornstarch, and half of the pumpkin pie spice in a small bowl.
Spray a 9x9-inch baking pan with cooking spray.
Generously dust the pan with some of the powdered sugar mix.
Add the aquafaba to a saucepan and cook until reduced by one half.
Add the aquafaba to the bowl of your standmixer. Beat until stiff peaks form.
Add in the cream of tartar and beat for another minute.
Add the vegan gelatin to a small bowl with ¼ cup of cold water, set aside.
Combine the sugar, corn syrup and 2 tablespoons of water in a small saucepan. Stir until it comes to a boil.
Boil until it reaches 245 F, about 10 minutes.
Slowly whisk the gelatin and vanilla extract into the sugar.
Drizzle the sugar mixture into the whipped aquafaba with the mixer running.
Beat for 12 minutes or until glossy and thick.
Add in the remaining pumpkin pie spice to the marshmallow mixture and beat until combined.
Pour the marshmallow into the dusted baking dish and allow to rest for at least 8 hours or until firm.
Transfer the marshmallows to a surface coated with the sugar mixture. Coat a knife or pizza wheel with cooking spray and cut the marshmallows into cubes. Dust with more of the powdered sugar blend.
To serve, toast, roast, or just enjoy on their own.