Position a rack in the lower third of the oven and preheat to 350 degrees F. Put the butter in a medium bowl. Brush the Bundt pan with some of the butter to lightly coat.

Cut the biscuits into quarters. Combine the hot cocoa mix and sugar in a large bowl and stir together.

Working in batches, toss one-third of the biscuits in the melted butter, roll them in the hot cocoa mixture to lightly coat and add them to the Bundt pan so they are nestled together in an even layer; sprinkle with one-third of the marshmallows and chocolate chips. Repeat to make 2 more layers of biscuits rolled in cocoa, the marshmallows and chocolate chips. Sprinkle the top with any leftover hot cocoa mixture and drizzle with any leftover butter.

Cover the pan with foil and bake for 35 minutes. Remove the foil and bake until puffed and golden brown, 10 to 15 minutes more. Loosen the bread from the sides of the pan with a knife or offset spatula. Carefully invert the pan onto a serving plate, remove the pan and serve hot.