Prepare the crust first and chill for an hour before adding the filling. Cool 1 more hour, and it's ready to enjoy!
Crust
step 1Mix the pecans, butter, and sugar in a mixing bowl with your hands until the butter melts and mixes evenly together. Press the pecan mixture into pie pan bottom and up the side.
step 2Refrigerate for 1 hour.
Filling
step 1Melt chocolate together in a double boiler, or in the microwave (depending on the microwave, about two minutes).
step 2Remove from the heat and let cool slightly.
step 3In a separate bowl add the egg yolks to orange liqueur, vanilla, and ½ cup of sugar. Whisk in until smooth and pale yellow.
step 4Place egg yolks, sugar, orange liqueur, and vanilla over double boiler and continue to whisk over simmering water until thickened.
step 5Remove from heat and continue to whisk until cooled, but not cold.
step 6Add chocolate to sugar mixture and stir until combined.
step 7Whip 1 cup of whipping cream to soft peaks and fold into chocolate mixture.
step 8Pour the chocolate mousse into the prepared pie shell and chill for at least an hour.
step 9Add ¼ cup sugar to the rest of the cream (1½ cups) and whip. Top the pie. Garnish with shaved chocolate, if desired.