Heat oven to 350 degrees. Grease a 9 or 10 inch pie pan and dust with granulated sugar.
Reserve 1 and 2/3 cup of dry cake mix, loosely packed. Beat remaining cake mix, water, oil and eggs in a medium bowl on low speed, scraping bowl constantly for 30 seconds.
Beat again on medium speed for 2 minutes and spread in prepared pie plate.
Bake until cake springs back when touched lightly in center, 30-35 minutes. Cool completely.
Reserve one tablespoon of the whipping cream. Beat remaining whipping cream and reserved dry cake mix until stiff. Fold in marshmallows, walnuts and chocolate chips and spread over cooled cake.
To make chocolate glaze heat the one tablespoon of reserved whipping cream with the butter and the ounce of semi-sweet chocolate over medium heat, stirring frequently until chocolate is melted and smooth.
Immediately drizzle the glaze over the top of the pie and refrigerate at least 2 hours before serving.