Preheat the oven:
Preheat to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper and lightly grease.

Make the graham cracker crust:
In a medium bowl, combine graham cracker crumbs, sugar, and melted butter. Press evenly into the bottom of the prepared pan. Set aside.

Prepare the brownie batter:

• In a medium saucepan, melt the butter and chocolate chips over low heat. Remove from heat and whisk in sugar until smooth.

• Add eggs one at a time, whisking well after each addition. Stir in vanilla extract.

• Sift together the flour, cocoa powder, salt, and baking powder. Fold the dry ingredients gently into the wet mixture until fully combined.

Assemble and bake:
Pour the brownie batter evenly over the graham cracker crust. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out mostly clean (a few moist crumbs are fine).

Add the s’mores topping:
Remove the brownies from the oven and immediately sprinkle mini marshmallows and chocolate chips over the top. Return to the oven for 5–7 minutes, or until the marshmallows are soft and slightly golden.

Cool and serve:
Allow brownies to cool for 10–15 minutes before slicing. Sprinkle extra graham cracker crumbs on top for added texture, if desired. Serve warm for gooey, melty perfection!