Prepare your pie crust, if making from scratch-- otherwise you can opt to keep it in the tin or remove it to another dish of your choosing. Keep in mind it's going in the freezer later.

Allow the ice cream to sit on the counter and soften a few minutes-- just until stir-able, not melted. Use a sturdy spatula to stir in the chocolate chips and 1 cup of marshmallows until evenly incorporated. Scoop the mixture into the pie crust.

Place the filled pie crust into the freezer so that it sits levelly. Allow it to freeze until hard, about an hour.

Add the cream to the bowl of a stand mixture. Whisk on medium speed for 2-4 minutes, or until the cream has thickened and soft peaks have formed. Remove the pie from the freezer and evenly spread the whipped cream out over top.

Top the center of the pie with the remaining 1/3 cup of marshmallows. Use a kitchen torch to lightly toast, if desired.

Heat a small skillet over warm heat. Add 1/3-1/2 of the hot fudge topping to the heated skillet and stir until melted. Working quickly, use a spoon to drizzle the hot fudge over the pie.

Slice and serve immediately, or return to the freezer for a maximum of two hours.