Place egg whites in a small bowl; let stand at room temperature for 30 minutes. Preheat oven to 400°. On a lightly floured surface, roll dough to 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim crust to 1/2 in. beyond rim of plate; flute edge. Combine flour and 1/2 teaspoon salt; set aside., In a large bowl, beat yolks until slightly thickened. Gradually add sugar, beating until thick and lemon-colored. Blend in the milk, lemon juice and zest. Add dry ingredients; mix well. Stir in pineapple., Beat egg whites and remaining salt until stiff peaks form; fold into filling. Spoon into pie crust., Bake 10 minutes; reduce oven temperature to 325°. Bake until top is puffed and lightly browned, 25-30 minutes longer. Cool on a wire rack. If desired, garnish with pineapple, cherries and whipped topping. Refrigerate leftovers.