Preheat the oven to 350°F. Line a 9x13 baking dish with parchment paper, set aside.

Place butter in a large microwave-safe mixing bowl, melt completely. Add sugar, cocoa, vanilla, and eggs. Whisk to combine well. Add flour, baking powder, and salt. Whisk until completely combined, but do not over mix.

Pour into the prepared baking dish. Press 24 sectioned pieces from the Hershey bars into the brownie batter. Each bar has 12 sections, you can place them in a 4x6 pattern to make them even in the pan. Press them into the batter with a spatula until they are covered. Bake for 20 minutes or until a toothpick comes out clean.

In a medium mixing bowl, break the remaining chocolate bars and graham crackers into bite-size pieces, stir in the marshmallows.

Once the brownies are cooked through, pour the marshmallow mixture over the top of the brownies and spread it evenly.

Place the brownies under the broiler until the marshmallows are golden, about 30 to 60 seconds. Don’t walk away from the oven. While broiling your food can go from zero to burnt in seconds.

Allow the brownies to cool on a cooling rack for 5-10 minutes. Spray a knife with nonstick pan spray to help prevent the blade from sticking.