Preheat oven to 350° F.
Whisk together 1 cup melted butter and 2 cups sugar.
Once butter is about room temperature, add in eggs and vanilla. Whisk to combine.
Add flour, cocoa, baking powder, and salt. Whisk until you have a cohesive, thick batter.
Spread batter evenly on top of the graham cracker crust.
Bake for 30-35 minutes or until a toothpick or knife comes out clean.
Take brownies out of the oven and top with marshmallows. Try to spread the marshmallows out evenly.
Sprinkle chocolate chips on top.
Turn on broiler function of oven.
Broil for 2 minutes or until marshmallows are just toasted on top.
Allow brownies to cool fully before cutting to allow marshmallow topping to set.