Preheat oven to 350 degrees F. In a large bowl, cream butter and sugar together until light and fluffy. Beat in the eggs and vanilla. Add the flour, cocoa, and salt.
Spread into a greased 9x13 pan. Bake for 25 minutes or until a toothpick inserted comes out with moist crumbs. DO NOT OVER BAKE!
Preheat the broiler. Sprinkle baked brownies with marshmallows and cereal. Broil 1-3 minutes on the upper middle rack. Watch carefully and remove once the marshmallows start to turn golden brown. Immediately sprinkle with chocolate. Cover with foil and let stand for 5 minutes until chocolate begins to melt. Remove foil and cool before cutting into squares.