For the pie crust: Combine the flour, sugar, salt and butter in a food processor and pulse until coarse, with small marbles of butter remaining. Sprinkle with 2 tablespoons of the ice water, then pulse until crumbly and the dough holds together when squeezed. (If too dry, add another sprinkle of water, but do not over mix.) Transfer the dough to a plastic bag, press into a disk and refrigerate for one hour.
Preheat the oven to 425 degrees F.
Roll out the dough on floured surface, then press it into a deep 9-inch pie plate. Trim the edges to leave 1 inch of overhang, fold it under and flute the edges. Cut a piece of parchment or nonstick foil to the size of the pie plate and use it to line the pie crust. Fill with pie weights and bake until golden, about 15 minutes. Remove the pie weights and return the pie dough to the oven to dry out, about 8 minutes.
Lower the oven to 325 degrees F.
For the filling: In a double boiler, melt the semisweet chocolate, bittersweet chocolate and butter, stirring frequently until smooth. Remove from the heat.
In a large bowl, mix together the pumpkin puree, evaporated milk, light brown sugar, eggs, cornstarch, vanilla, cinnamon, ginger, nutmeg, cloves and salt. Fold in the melted chocolate mixture. Set the pie plate on a baking sheet and pour the filling into the crust. Bake until the center of the pie has just about set but still has a slight jiggle, about 1 hour. Let cool completely before serving. Top with chocolate shavings.