Preheat the oven to 350 degrees F.
In a large bowl, beat together the butter, sugar, brown sugar, and vanilla. Add the eggs and beat well. Add the flour, baking soda, salt, and mix to incorporate. Fold in the chocolate chips and walnuts.
Pour into an ungreased 9 by 13-inch baking dish, spreading the dough into the corners as necessary and bake until puffed and golden brown, 25 to 30 minutes.
Remove from the oven and cool for 10 minutes in the dish. Pour the Chocolate Icing over cooked chocolate chip cookies. Sprinkle with marshmallows and coconut and let sit until firm, about 1 hour. Cut into squares and serve.
Yield: 15 to 18 bars