Stepwise Method:

• In a mixing bowl, combine the melted unsalted butter, crushed graham cracker crumbs, sugar, and a pinch of fine salt. Mix until well combined. Press this mixture evenly into the bottom of the prepared baking pan to form a crust.
• In a medium saucepan, melt the 8 tablespoons of unsalted butter and the chopped unsweetened chocolate over low heat, stirring constantly until smooth. Remove from heat and let it cool slightly.
• In a large bowl, whisk together the packed light brown sugar and white sugar with the chocolate mixture until well blended. Add the vanilla extract and fine salt, mixing until incorporated.
• Add the cold eggs one at a time, whisking vigorously after each addition until the batter is smooth and glossy.
• Gently fold in the all-purpose flour until just combined. Be careful not to overmix, as this can lead to dense brownies.
• Pour the brownie batter over the graham cracker crust in the baking pan, spreading it out evenly.
• Bake in the preheated oven for about 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
• Remove the brownies from the oven and immediately top them with mini marshmallows and halved peanut butter cups. Return to the oven for an additional 5-7 minutes, until the marshmallows are puffed and golden.
• Once out of the oven, drizzle the melted peanut butter over the top of the brownies. Allow the brownies to cool in the pan for at least 15 minutes before cutting into squares.