preheat the oven to 350˚

mix the flour, brown sugar, baking soda, and salt

cut the butter into small pieces toss it together with the flour mix

then use a pastry blender OR 2 knives to cut the butter into the flour until it resembles fine crumbs

press it into a 9X13 pan

bake for 23 minutes

cut the marshmallows in half while the base bakes

when the cookie base comes out make layers of marshmallows and chocolate on top of it

sprinkle with extra graham cracker crumbs if desired (this makes them messy but it looks good!)

bake again for 5-7 minutes JUST until the marshmallows get soft and gooey, overbake it and they'll melt into oblivion