Mix the crushed chocolate sandwich cookies and melted butter. Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate. Place the crust in the freezer while you prepare the filling.

For a shortcut, use a store-bought 9-inch graham cracker crust. Keep it in its disposable pie pan and add the filling directly to the crust. No baking or freezing beforehand is necessary.

Combine the marshmallows and milk in a medium saucepan. Cook over low heat, stirring frequently, until the marshmallows are completely melted and the mixture is smooth.

Remove the saucepan from the heat. Add the chocolate chips and stir until completely melted and smooth. Stir in the strong brewed coffee or Kahlúa.

Let the chocolate mixture cool completely to room temperature, stirring occasionally. Do not refrigerate it, or it may begin to set before you fold in the whipped cream.

If using heavy cream, beat it until medium peaks form. Gently fold the whipped cream or thawed frozen nondairy whipped topping into the cooled chocolate mixture in two or three additions.

Spoon the filling into the prepared crust and smooth the top. Freeze for at least 6 hours or overnight.

Let the pie stand at room temperature for 10 to 15 minutes before slicing. If desired, top with additional whipped cream or thawed frozen nondairy whipped topping. I used an entire 8-ounce container on top of the pie. Garnish with grated semisweet chocolate.