Preheat your oven to 325℉.
In a medium bowl, combine the walnuts, butter, and sugar.
Press the walnut mixture onto the bottom and sides of a 9-inch pie plate, creating a firm, even crust.
Bake the crust in the preheated oven for 12 to 14 minutes, or until the edges are golden. Let it cool.
Combine the chocolate, marshmallows, and whole milk in a medium saucepan.
Cook this mixture over medium heat, stirring until melted. Remove from heat and cool for 30 minutes.
In a medium bowl, beat the heavy whipping cream and vanilla extract until soft peaks form.
Add the cooled chocolate mixture to the whipped cream, stirring gently until combined.
Scrape the filling into the baked pie crust and smooth the top.
Top with Cool Whip and sprinkle with chopped chocolate toffee candy bars.
Freeze the pie for 8 hours or until firm. Let it sit at room temperature for 10 to 15 minutes before slicing.