01 -
Preheat oven to 375 degrees Fahrenheit. Line a 13x9-inch pan with parchment paper, leaving a 2-inch overhang on the sides.
02 -
Place graham crackers in a layer covering the full pan, breaking graham crackers into sections as needed to fit properly.
03 -
In the bowl of an electric mixer with the paddle attachment, cream together the butter and both sugars. Add eggs and vanilla. Mix and scrape bowl. In a large bowl, whisk together the flour, salt and baking soda. Add the flour mixture, chocolate chips, and mini marshmallows to the butter mixture. Mix until just combined.
04 -
Evenly distribute the dough on top of the graham crackers and press flat. Top with additional mini marshmallows if desired.
05 -
Bake at 375˚F for 25-30 minutes or until golden brown and a toothpick comes out clean from the center. Cover with foil if cookie dough browns faster than center bakes.
06 -
Remove from oven and place chocolate bar pieces on top while still warm. Allow to cool for 20-30 minutes before lifting bars out of pan to cut and serve. NOTE: Chocolate bars may stay quite soft and melty at room temperature.