Line a baking sheet with parchment paper to prevent the balls from sticking.
In a microwave-safe bowl, melt the butter and chocolate chips together in the microwave in 30-second intervals, stirring in between, until smooth and completely melted.
Add the mini marshmallows to the melted chocolate mixture and stir until the marshmallows are fully coated.
In a large mixing bowl, combine the Rice Krispies cereal, cocoa powder, and a pinch of salt.
Pour the melted chocolate and marshmallow mixture over the Rice Krispies and gently fold until all the dry ingredients are well coated.
Allow the mixture to cool slightly, then use your hands to shape the mixture into small balls, about 1 inch in diameter, and place them on the prepared baking sheet.
Once all the balls are formed, refrigerate for about 30 minutes to set.
If desired, drizzle additional melted chocolate over the cooled balls for decoration.