Preparation / Directions:
Pastry: Mix flour, sugar and salt in medium bowl. Cut in margarine, using pastry blender or crisscrossing 2 knives, until particles are size of small peas. Add 1/2 cup milk and the egg yolks; mix gently with fork until well blended, adding additional milk, 1 tablespoon at a time, until all flour is moistened and pastry almost cleans side of bowl.
Filling: 1. Heat oven to 350 degrees. Gather pastry into a ball; cut in half. Shape each half into flattened round on lightly floured cloth-covered surface. Roll 1 round into rectangle, 18x13 inches, with floured cloth-covered rolling pin. Fold pastry into fourths; unfold and ease into ungreased jelly roll pan, 15 1/2x10 1/2x1 inch.
2. Stir lemon peel into pie filling. Carefully spoon pie filling over pastry; spread evenly. Sprinkle with hazelnuts.
3. Roll other round of pastry into rectangle, 15 1/2x10 inches. Fold into fourths; cut slits so steam can escape. Place over filling and unfold. Beat reserved egg whites from Pastry recipe and the water; brush over top crust. Sprinkle with sugar.
4. Bake about 1 hour or until golden brown and juice begins to bubble through slits in crust. Cool 1 hour. For servings, cut into 5 rows by 3 rows.