1. Preheat the oven to 350 degrees F.
Make the crust:
2. Combine the pecans, flour, brown sugar, nutmeg, and butter, in
a food processor and pulse until the nuts are crushed and the butter
is incorporated. Remove from processor and press the crust over
the bottom and up the sides of the pan. Bake for 15 minutes; then
set aside on a rack to cool.
Make the filling:
3. In a heavy saucepan, heat the cream until it just begins to bubble
around the edges; be careful not to let it scorch.
4. In a double boiler set over barely simmering water, melt the
chocolate, stirring until smooth. Gradually add the hot cream to
the melted chocolate, stirring constantly to combine. Stir in the
egg yolks and vanilla until fully blended. Cook over low heat until
thickened and hot, 8 to 10 minutes. Pour the filling into the prebaked
crust and chill for at least 4 hours.
Make the whipped cream:
5. Put the cream and powdered sugar in a chilled bowl and beat with
the electric mixer on medium speed until stiff peaks form.
6. Before serving, pipe the whipped cream with a pastry bag over
the filling in a crosshatch pattern or spoon it on decoratively.
Sprinkle the grated chocolate over all.
7. Remove the sides of the pan and transfer the pie to a plate