Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, mix together peanut butter, granulated sugar, brown sugar, egg, and vanilla extract until smooth.
Fold in the mini marshmallows, crushed graham crackers, and chocolate chips. Evenly divide the cookie dough between the prepared paper liners. Bake for 12-15 minutes.