01 -
Preheat the oven to 350°F to ensure uniform baking of the bars.
02 -
In a large mixing bowl, whisk together graham cracker crumbs, unsweetened cocoa powder, and powdered sugar until evenly blended.
03 -
Pour in the melted butter and sweetened condensed milk. Stir with a spatula until the mixture is fully incorporated and forms a thick, cohesive batter.
04 -
Gently fold in mini marshmallows, chocolate chips, and chopped nuts if using, ensuring an even distribution throughout the mixture without overmixing.
05 -
Transfer the batter to a greased baking pan, spreading it evenly and smoothing the top. Bake for 25-30 minutes, or until the edges are set and the center is slightly firm.
06 -
Remove the pan from the oven and allow to cool completely. Once cooled, cut into bite-sized squares using a sharp knife and serve.