1. Combine first 3 ingredients in a large bowl. Cut in butter with a pastry blender until mixture resembles coarse meal.
2. Stir together egg yolks and 6 tablespoons water in a small bowl. Add egg yolk mixture to flour mixture, stirring with a fork until dry ingredients are moistened and dough starts to form a ball. (If dough appears dry, add 1 tablespoon water.) Divide in half, forming 2 balls; flatten slightly into disks, and wrap with plastic wrap. Chill at least 30 minutes.