Preheat oven to 350°F. Line a 9x13" baking dish with parchment paper, and spray well with nonstick cooking spray.
Mix together butter and brown sugar with eggs and vanilla, in a stand mixer with the paddle attachment (or with a handheld mixer).
Once combined, add in flour, baking soda, salt, and graham cracker crumbs. Mix until cookie dough comes together.
Use 3/4 of the dough and press into the bottom of the baking dish. Spread marshmallow cream over pressed cookie dough. (Be sure to spray the spatula with some cooking spray so the marshmallow cream doesn't stick.)
Sprinkle the chocolate chips over the cream, then drop pieces of the remaining cookie dough over. You can drop the dough in dollops on top of the chocolate chips, so it doesn't squeeze out the marshmallow cream.
Bake for 22-24 minutes. Once the cookie edges turn a golden brown color and start to pull away from the edge, they're done. Let cool and set before cutting. Enjoy!