Microwave ¼ cup heavy whipping cream for 45-60 seconds in microwave.
Whisk the hot chocolate mix into the whipping cream, until chocolate is completely blended, set aside and let cool.
Using a mixer, cream the cream cheese and powdered sugar together well.
Optional: Measure out 2 tablespoons of the whipped hot chocolate mix and set aside for drizzle on top if you want the swirl effect on top of the pie.
Add the remainder of the whipped hot chocolate mixture to the cream cheese/powdered sugar mixture and mix until well blended.
Mix in the 1 ½ cups of whipped topping to the chocolate mixture and mix until combined, then pour filling into pie crust and smooth out.
Optional: Drizzle the 2 tablespoons of the reserved hot chocolate sauce on top of the pie and swirl around.
Add remainder of whipped cream to center or outside edge of pie.
Add some marshmallows.
Dust some cocoa powder on top if desired.
Refrigerate pie for at least 4 hours before serving or transfer to freezer and let thaw about 15 minutes before cutting and serving.