**Prepare the Crust:** In a medium bowl, whisk together flour and salt. Add cold butter and use a pastry cutter or your fingers to mix until the texture resembles coarse crumbs. Gradually add ice water, one tablespoon at a time, mixing until the dough comes together. Form into a disk, wrap in plastic, and chill for 30 minutes. Roll out the dough on a floured surface and transfer it to a 9-inch pie dish. Trim excess dough and crimp the edges. Chill for another 15 minutes. Preheat the oven to 375°F (190°C). Line the crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, then remove weights and bake for another 10 minutes. Let cool completely.

**Make the Filling:** Melt the chopped chocolate in a heatproof bowl over a saucepan of simmering water (double boiler method). Stir until smooth, then set aside to cool slightly. In a bowl, whip the heavy cream to stiff peaks and refrigerate. In another bowl, beat the eggs and sugar together until pale and fluffy, about 5 minutes. Add the melted chocolate and vanilla extract, mixing until combined. Gradually add softened butter, a tablespoon at a time, beating until the mixture is smooth and silky. Fold in the whipped cream gently.

**Assemble the Pie:** Pour the chocolate filling into the cooled crust and smooth the top with a spatula. Refrigerate for at least 4 hours or until set.

**Prepare the Topping:** Whip the chilled heavy cream and powdered sugar together until soft peaks form. Spread or pipe the whipped cream over the chilled pie. Garnish with chocolate shavings or cocoa powder, if desired.