Preheat the oven to 350°F (175°C).
In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Mix until well combined.
Press the crumb mixture evenly into the bottom and up the sides of a 9-inch pie dish to form the crust.
Bake the crust in the preheated oven for about 10 minutes or until lightly golden. Remove from the oven and let cool.
In a double boiler or microwave-safe bowl, melt the chopped semisweet chocolate. Stir occasionally until smooth and set aside to cool.
In another bowl, whisk together cocoa powder, heavy cream, sugar, eggs, vanilla extract, and salt until blended. Gradually mix in the melted chocolate.
Pour the chocolate filling into the cooled graham cracker crust.
Bake the pie in the oven for about 15 minutes, or until the filling is set but slightly wobbly in the center. Allow to cool at room temperature, then refrigerate for at least 2 hours before serving.
For the topping, whip the heavy whipping cream with the powdered sugar until stiff peaks form.
Spread the whipped cream over the top of the chilled mud pie and garnish with chocolate shavings.