In a medium bowl stir together flour, 1/4 cup sugar, and salt. Use a pastry blender to cut in butter until pieces are pea size. Stir in nuts. In a small bowl stir together 2 eggs yolks and ice water. Gradually stir egg yolk mixture into flour mixture. Use your fingers to gently knead the pastry just until a ball forms. Cover with plastic wrap and chill for 30 to 60 minutes or until pastry is easy to handle.

Preheat oven to 450 degrees F. On a lightly floured surface, use your hands to slightly flatten the pastry. Roll pastry from center to edges into a circle 11 inches in diameter. Wrap pastry around the rolling pin. Unroll it into a 9-inch tart pan with a removable bottom. Press pastry into fluted sides of tart pan; trim edges. (If pastry breaks when it is transferred to the pan, press together to seal.) Line pastry with a double thickness of foil. Bake for 8 minutes. Remove foil. Bake for 5 to 6 minutes more or until golden. Reduce oven temperature to 375 degrees F.

Meanwhile, in a medium saucepan combine 1-1/4 cups whipping cream and 2 tablespoons hazelnut liqueur. Bring mixture just to simmering over medium heat. Remove from heat. Stir in chopped chocolates until mixture is smooth. Stir in 1 egg yolk until just combined. Pour mixture into baked tart shell. Bake for 25 minutes or until nearly set. Remove from oven and cool completely in pan on a wire rack.

In a medium mixing bowl, beat together cream cheese, 2 tablespoons sugar, and 1 tablespoon hazelnut liqueur with an electric mixer on medium speed until smooth. Beat in 1 cup whipping cream just until soft peaks form. Spoon mixture into a pastry bag fitted with a large star tip. Pipe mixture on top of cooled tart. If desired, top with chocolate-dipped hazelnuts and chopped dark chocolate. Makes 12 servings.

Prepare as directed through Step 3. Cover and refrigerate up to 3 days. Before serving, let stand at room temperature about 1 hour and continue as directed.