Preheat your oven to 350°F. Grease and line a 9in baking dish with parchment paper.
In a heatproof bowl set over a saucepan of simmering water, melt the dark chocolate and unsalted butter, stirring until smooth and melted together.
1 cup unsalted butter, 10 ounces dark chocolate
Remove bowl from heat (dispose of water) and whisk/mix in the granulated sugar into the melted chocolate mixture until well combined.
1 1/2 cups granulated sugar
Add in the eggs, one at a time, stirring after each egg added.
4 large eggs
After all eggs are added, stir in the vanilla extract.
1 tsp vanilla extract
Gradually fold in the all-purpose flour and salt, mixing until a smooth brownie batter forms.
1 cup all-purpose flour, 1/2 tsp salt
In a separate bowl, crush graham crackers into crumbs using a rolling pin or a food processor. (You can also buy boxed graham cracker crumbs that will work too!)
1 cup graham cracker crumbs
Pour HALF of the brownie batter into the prepared baking dish, smoothing it out evenly. Sprinkle HALF of the graham cracker crumbs over this layer.
Pour the remaining brownie batter to form the second layer. Smooth out evenly and top with the remaining graham cracker crumbs.
Place the baking dish in the preheated oven and bake for 30-40 minutes or until the edges of the brownie are starting to firm.
Remove pan from oven and sprinkle the marshmallows over the top of the brownie (BE CAREFUL the pan in hot).
2 cups mini marshmallows
Place plan back in oven and cook for approx. 10 minutes or until marshmallows are golden brown.
Once the bars are baked and cooled, drizzle the melted chocolate over the marshmallow topping.
1/4 cup melted chocolate