Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a mixing bowl, cream together the butter, peanut butter, granulated sugar, and brown sugar until smooth. Add the eggs and vanilla, mixing well.
In a separate bowl, combine the flour, graham cracker crumbs, baking soda, and salt. Gradually mix this dry mixture into the wet ingredients until just combined.
Drop tablespoon-sized portions of dough onto the prepared baking sheet. Bake for 10 minutes or until lightly golden.
Remove from the oven and let cool for a few minutes. While cooling, mix the mini marshmallows, chocolate chips, and creamy peanut butter in a bowl.
Spread a spoonful of the marshmallow-chocolate filling onto half of the cookies, then top with the remaining cookies to create sandwiches.
Notes
Store cookies in an airtight container to maintain freshness. You can also try adding chopped nuts for extra crunch.