Preheat oven to 350. Line an 8x8" or 9x9" baking dish with parchment paper, or foil.
Mix together butter and sugar with egg and vanilla. Mix in flour, baking soda, salt, and graham cracker crumbs until cookie dough comes together.
Use 3/4 of the dough and press into the bottom of the baking dish. Spread marshmallow creme over pressed cookie dough. (Be sure to spray the spatula with some cooking spray so the marshmallow creme doesn't stick.)
Sprinkle the chocolate chips over the creme, then press the remaining cookie dough over. Use a spoon to drop the dough in dollops on top of the chocolate chips, then press in with hands or spatula.
Bake for 18-20 minutes. Let cool before cutting. Enjoy!