For the crust:
1 1/2 cups graham cracker crumbs
6 tablespoons unsalted butter; melted
For the brownie layer:
8 tablespoons (1 stick) unsalted butter
4 ounces semi-sweet chocolate chips
1 cups sugar
1 teaspoon vanilla extract
1/4 teaspoon salt
1/2 cup all-purpose flour
For the topping:
20 large marshmallows; cut in half
Preheat oven to 350 degrees. Line an 8-inch-square metal baking pan with foil and spray lightly with nonstick cooking spray.
Combine the graham cracker crumbs, 6 tablespoons of melted butter in a bowl and mix until the crumbs are moistened. Press the crumbs evenly into the bottom of the pan and bake at 350 degrees for 7 minutes. Allow crust to cool on wire rack.
Turn the oven temperature up to 400 degrees and prepare the brownie layer.
In top of a double boiler set over barely simmering water, or on low power in a microwave, melt butter and chocolate together. Stir often, and remove from heat when a few lumps remain. Stir until smooth.
Add in sugar, vanilla and salt. Followed by the eggs(one at a time) and finally the flour. Stir until very smooth, about 1 minute, until mixture pulls away from sides of bowl. Scrape batter into prepared pan and bake for 18 minutes.
Let cool completely, then lift out using the foil and place brownies onto a broiler safe pan. Move your oven rack about 6 inches from your broiler and preheat your broiler to low.
Layer marshmallows (sticky side down) across the top and toast under the broiler until golden, about 2 minutes. Keep an eye on them because they burn easy and quickly.
Cool and cut into squares....if you can wait for them to cool!