Begin by blind baking your Marie Callender's frozen pie crust according to package instructions. Allow the crust to cool completely before filling.
In a double boiler over medium heat, melt the 8 oz. of semisweet baking chocolate. Stir occasionally until smooth and fully melted. Set aside to cool slightly.
In a mixing bowl, pour in 1 cup of heavy whipping cream. Add the 1 teaspoon of vanilla extract and, if desired, 1/4 cup of powdered sugar. Whip the cream until soft peaks form.
In another bowl, combine 2 cups of cold milk with the 15.1 oz. package of instant chocolate pudding. Whisk together for about 2 minutes until thickened.
Once the melted chocolate has cooled slightly, fold it into the chocolate pudding mixture. Use a rubber spatula to combine gently.
Gently fold the whipped cream into the chocolate pudding mixture until no streaks remain.
Pour the chocolate filling into the cooled pie crust, spreading it evenly. Smooth the top for an elegant finish.
Cover the pie with plastic wrap and refrigerate for at least 4 hours, or until set.
Before serving, top the pie with chocolate shavings. Slice and serve chilled.
