2tbspchopped marshmallowsmini are easiest to work with
Preheat oven to 350F
In a mixing bowl, stir together peanut butter, sugar, egg, cinnamon, ginger and salt with a wooden spoon or rubber spatula until the egg is fully incorporated.
Stir in chocolate chips and marshmallows. This may be easier to do by kneading with your hands.
Place a piece of parchment paper on a baking sheet. Roll out or scoop 1 1/2" balls of dough and place them 1" apart on the parchment paper. Using a fork, press down on each cookie once. Turn the fork 90 degrees and press down again. This will make the cross-hatch design on it.
Bake for 10 min. They are done when the sides begin to firm up and any exposed marshmallows are slightly golden brown.
Allow to firm up outside the oven on the baking sheet for 5 minutes before transferring to a cooling rack.
Optionally allow to cool completely on the cooling rack.