1/2 cup butter, room temperature
1/4 cup brown sugar
1/2 cup sugar
1 large egg
1 tsp vanilla
1 1/3 cups flour
1/4 tsp salt (optional)
3/4 cup graham cracker crumbs (approximately 5 full graham crackers)
1 tsp baking powder
2 or 3 super-sized (5 oz.) chocolate bars (e.g. Hershey’s)
1 1/2 cups marshmallow creme/fluff (or mini marshmallows if you must!)
Preheat oven to 350. Grease bottom of pan.
In a large bowl or stand mixer, cream together butter and sugar until light. Beat in egg and vanilla.
In a small bowl, whisk together flour, graham cracker crumbs, baking powder and salt.
Add to butter mixture and mix at a low speed until combined.
Divide dough in half and press half of dough into an even layer on the bottom of the prepared pan. Place chocolate bars over dough. Two 5 oz. Hershey’s bars should fit perfectly [for 8 by 8] side by side, but break the chocolate (if necessary) to get it to fit in a single layer. [use 3 Hershey's for 12 by 8 pan]
Spread marshmallow fluff evenly over the chocolate layer.
Place remaining dough in a single layer on top of the creme. This is most easily done by putting the second half of the dough in a gallon size freezer bag. Use your palms or rolling pin to flatten it out, and then use scissors to cut down both long sides of the bag, so it will open up book-style. Open it up carefully, and the dough will stick on one side of the bag. Then place the bag, dough side down, on the other three layers. From there peel the bag up and carefully spread the dough where it is uneven.
Bake for 30 to 35 minutes, until lightly browned. Cool completely or almost completely for the melty factor before cutting into bars.