S'mores Bars

I made these for my nephew's birthday and they were good, but extremely rich!  I got the recipe off pinterest, but it is a Betty Crocker recipe and quite easy.

1 pouch (1 lb 1.5 oz.) Betty Crocker sugar cookie mix
1 cup graham cracker crumbs ( I just crushed mine in a ziploc bag)
1 cup melted butter
3 cups chocolate chips
4 1/2 cups miniature marshmallows

Heat oven to 375 degrees.  In a large bowl, stir together cookie mix and graham cracker crumbs.  Stir in melted butter until a soft dough forms.  Press into ungreased 13x9 inch pan.  Bake 18-20 minutes or until set. Immediately sprinkle chocolate chips over crust.  Let stand 3-5 minutes.  Once chocolate becomes shiny, spread the chocolate evenly over the crust.  Set oven to broil and sprinkle marshmallows over melted chocolate. Broil the top until the marshmallows are toasted.  Cool 10 minutes and serve warm.