Line the bottom of a 9 x 13" pan with parchment, non-stick spray, and powdered sugar.
In a bowl fitted with a stand mixer and a whisk attachment, combine gelatin and cold water. Do not mix yet. Let this sit while you prepare the syrup.
In a saucepan, combine sugar, corn syrup, salt and 1/2 cup cold water. Cook over medium heat until sugar dissolves. Put the heat up to high and let the sugar cook until it comes to a rolling boil. It may take a few minutes.
Remove the syrup and add it to the bowl with gelatin.
On high speed, mix until the mixture is thick and fluffy.
Using an offset spatula, spread the batter evenly in the baking dish.
Using an offset spatula, spread the batter evenly in the baking dish.
Turn marshmallows onto a cutting board dusted with powdered sugar. Use a sharp knife to cut 1 1/2" squares.
Break a graham cracker in half. Put peanut butter and white chocolate on one side.
Put marshmallow on the other side and put in the microwave for 5 seconds.
Sandwich the two together and sprinkle sides with sprinkles.