Line bottom of an 8" springform pan with wax paper or parchment paper.
Position knife blade in food processor bowl; add first 5 ingredients. Pulse 10 to 12 times or until pecans are finely chopped and mixture is combined. Firmly press mixture into bottom of prepared pan.
Bake at 325° for 14 minutes; cool in pan on a wire rack. Carefully remove sides of springform pan. Invert crust onto a serving plate. Carefully remove bottom of pan and paper. Replace sides of springform pan around crust on plate.
Place chocolates in top of a double boiler; bring water to a boil. Reduce heat to low; cook until chocolate melts. Remove from heat.
Bring whipping cream to a simmer in a saucepan over medium heat (do not boil). Gradually stir about one-fourth of hot cream into egg yolk; add to remaining hot cream, stirring constantly.
Cook over medium heat just until mixture reaches 160°. Gradually whisk cream mixture into melted chocolate, stirring until thick and blended. Pour chocolate over crust in prepared pan. Cover and chill thoroughly.
Run a knife around edge of pan and carefully remove sides of pan. Let torte stand 10 to 15 minutes before serving. Top each serving with whipped cream.