In the large bowl of a stand mixer fitted with the paddle attachment, beat cream cheese and Marshmallow Fluff on medium-high speed until light and fluffy, about 1 minute.
Add hot cocoa mix, cream, and cocoa powder and beat on low speed until just combined, 1 to 2 minutes. Increase speed to medium-high and continue to beat until dip is smooth and cocoa mix has fully dissolved, 2 to 3 minutes.
Transfer dip to a serving bowl. Top with whipped cream, marshmallows, and sprinkles (if using). Serve with cookies alongside.
