Preheat oven to 350°F and grease a 9x13-inch dish.
Mix cake ingredients until smooth and pour into the dish.
Bake 28–32 minutes or until toothpick comes out clean.
Let cake cool 15 minutes, then poke holes with wooden spoon handle.
Whisk pudding, milk, hot cocoa mix, and condensed milk.
Pour pudding mixture over cake, spread gently to fill holes.
Refrigerate at least 2 hours or overnight for best flavor.
Top with Cool Whip, marshmallows, chocolate chips, and fudge drizzle.
Chill 30 more minutes before serving.