Preheat oven to 350°F. Line an 8 inch square metal pan with nonstick foil.

Melt the 4 tablespoons of butter in a 3 quart saucepan. Stir in the sugar and graham cracker crumbs and mix well. Press into the bottom of the pan and bake at 350 F for 5 minutes. Let cool slightly while you make the brownie batter.

Wipe out the 3 quart saucepan and make the brownie base. Melt the remaining 8 tablespoons butter in the saucepan. Stir in the sugar and the cocoa powder. Reduce heat to low and stir gently for about 30 seconds to warm the sugar. Turn off the heat and let the sugar mixture sit for 5 minutes. Stir in the salt and vanilla. Add the cold eggs, whisking or stirring just until mixed, then mix the flour and baking powder together in a little cup and stir them into the batter. Let the batter cool slightly, then stir in the chocolate chips.

Spread the batter in the pan and bake for 23 minutes. Remove brownies from the oven, sprinkle marshmallows over the top, then put under the broiler (about 4 inches) for about a minute or until the marshmallows brown. Alternately, you can skip the broiler and just put them back in the oven for a few minutes until the marshmallows puff up and then if you have one, brown them with a torch. Let the brownies cool completely before cutting, and for neater slicing, chill before doing. Bring back to room temperature before serving.