Brownies with Marshmallow Topping

Make the graham cracker crust

1. Preheat the oven to 350°F (177°C).
2. Butter the bottom and sides of an 8-by-8-inch baking pan and line it with parchment paper cut to fit the bottom of the pan. Butter the parchment paper.
3. In a small saucepan over low heat or in a bowl in the microwave, melt the butter.
4. In a medium bowl, combine the graham cracker crumbs, sugar, and salt. Add the melted butter and mix well. Press the crumb mixture evenly over the bottom of the prepared pan and flatten it with the back of a spatula.
5. Bake the graham cracker crust just until the crumbs are golden brown around the edges, about 10 minutes.

Make the chocolate brownies and marshmallow topping

1. While the graham cracker crust bakes, place a medium heatproof bowl over a saucepan filled with 1 to 2 inches of water (make sure the water doesn’t touch the bottom of the bowl). Add the butter and chocolate to the bowl and place the saucepan over very low heat, stirring occasionally, until the chocolate melts. Place the bowl on the counter and let it cool for 5 minutes.
2. Add the sugar to the melted chocolate mixture and stir to combine. Slowly whisk in the eggs, 1 at a time, and mix until incorporated. Add the vanilla and stir until incorporated. Slowly add the flour in 2 batches and stir just until incorporated after each addition. Stir in the salt just until combined. Do not overmix.
3. Scrape the brownie batter onto the warm graham cracker crust and slide it back into the oven until the brownies are set and the center is still a bit soft, 30 to 40 minutes. They should be soft but still a bit gooey when tested with a toothpick—you want moist crumbles on the toothpick. Start checking them after 25 minutes.
4. Remove the pan from the oven, adjust the oven rack to the top position, and turn on the broiler.
5. Arrange the marshmallows evenly on the brownies and slide the pan back in the oven. Broil until the marshmallows are softened and lightly toasted, 45 seconds to 1 minute. (Don't turn your back on the marshmallow-topped brownies.)
6. Carefully pull the pan from the oven and, using the back of a spoon, gently press down on the marshmallows to flatten them slightly. (You want to do this slowly so they don’t stick to your spoon.) Return the pan to the oven and broil until the marshmallows are nicely toasted, another 15 to 30 seconds.☞ TESTER TIP: Before smooshing the marshmallows, you can spray the back of your spoon with nonstick spray to minimize goo clinging to it.
7. Let the brownies cool in the pan for at least 1 hour. [Editor's Note: We know, we know. Nearly impossible! But it ensures the brownies—in all their magnificent layers—fully set. Trust us.]
8. Run a sharp knife under warm water and then run the knife along the edge of the pan. Cut the s'mores brownies into squares, ensuring each square has some ooey, gooey, toasted marshmallow on top. After each cut, run the knife back under warm water, wipe clean, and repeat. Go ahead and enjoy. Campfire optional.