Preheat Oven: Preheat the oven to 350°F (175°C) and grease an 8×8-inch baking pan or line it with parchment paper.

Make the Brownie Batter: In a medium bowl, whisk together the melted butter and sugar until smooth. Add the eggs and vanilla extract, and whisk until combined.

In a separate bowl, sift together the flour, cocoa powder, salt, and baking powder. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Pour the brownie batter into the prepared baking pan and spread it out evenly.

Bake the Brownies: Bake the brownies in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Remove from the oven and set aside to cool slightly.

Prepare the S’mores Topping: In a small bowl, combine the graham cracker crumbs and melted butter. Stir in the chocolate chips.

Assemble the S’mores Brownies: Once the brownies have cooled slightly, sprinkle the graham cracker crumb mixture evenly over the top. Add the mini marshmallows on top, spreading them out evenly.

Broil the Topping: Place the brownies under the broiler for 1-2 minutes, or until the marshmallows are golden brown and toasted (watch closely to prevent burning!).

Cool and Serve: Let the brownies cool completely before slicing into squares. Serve and enjoy the gooey, s’mores-inspired treat!