1. For the filling, place cornstarch, sugar, and salt in a medium-sized pot over a medium-low flame and whisk for one minute. Add creamer and yolks while whisking. Whisk custard continuously for three to four minutes, until it has thickened and starts to bubble.
2. Remove from flame and add margarine and chocolate. Whisk until chocolate has melted completely and filling has a smooth consistency.
3. Pour chocolate custard into pie crust and place in the fridge for at least three hours.
4. For the topping, beat all ingredients with an electric mixer until stiff; spread over pie.
5. With a peeler or a knife, shave off curls of extra chocolate and sprinkle over pie. Refrigerate for at least eight hours to set.