Preheat your oven to 350°F (175°C). In a food processor, pulse about 10 graham crackers until finely crushed. In a mixing bowl, combine the crushed graham crackers, 1/4 cup of melted unsalted butter, and 1/4 cup of sugar until moistened. Press into a parchment-lined 9x13 dish to form a crust.

Prepare the brownie mix according to package instructions and pour the brownie batter over the crust in the baking dish. Smooth the top with a spatula.

Bake for 22-25 minutes until edges look set. Check for moist crumbs with a toothpick inserted in the center. Remove from oven and let sit for a few minutes.

Sprinkle a layer of miniature marshmallows and chocolate chips over the top immediately after removing from oven to melt into the brownies.

Switch your oven to broil and return brownies to the oven. Broil for 2-3 minutes until marshmallows puff and turn golden brown, watching closely.

Let the S'Mores Brownies cool for about 10-15 minutes before cutting into squares.