Preheat your oven to 350°F (175°C). Line an 8x8 inch pan with parchment paper.

Melt the butter in a small saucepan over low heat. Let it cool slightly before using.

In a bowl, whisk together sugar and eggs until smooth. Add vanilla and mix well.

Sift cocoa powder into the egg mixture. Stir until fully combined and chocolatey.

Add flour, salt, and baking powder. Mix gently until a smooth brownie batter forms.

Pour brownie batter into the prepared pan. Spread evenly with a spatula.

Sprinkle chocolate chips over the top of the brownie batter evenly.

Bake in preheated oven for 20 minutes. Remove and add mini marshmallows on top.

Sprinkle graham cracker pieces over the marshmallows. Press lightly without flattening.

Return pan to oven and bake for 10–15 minutes until marshmallows turn golden brown.

Let brownies cool in the pan for 15 minutes. Then lift out using parchment paper.

Use a sharp knife to cut the brownies into 12 squares. Serve warm or at room temperature.