Instructions: Pat dough evenly in bottom of prepared pan. Use fork to pierce dough all over. Bake on middle rack 30 to 40 minutes or until edges are lightly browned and top pale golden (do not brown).

Meanwhile, to prepare lemon curd topping: Use fine grater to remove 2 teaspoons lemon peel (yellow portion only). Transfer peel to medium bowl; suspend strainer over bowl and place near range.

Squeeze lemons and strain. You need 6 tablespoons lemon juice.

Combine egg yolks and sugar in heavy nonreactive saucepan; beat until well blended. Stir in lemon juice, butter and salt.

Cook over medium-low heat, stirring constantly (be sure to scrape sides of pan) until thickened. Mixture should thickly coat wooden spoon but still be liquid enough to pour (similar to consistency of hollandaise sauce).

Mixture will change from translucent to opaque and begin to take on a yellow color on back of wooden spoon. Do not allow to boil, or mixture will curdle. Whenever steam appears, remove pan briefly from heat, stirring constantly, to keep mixture from boiling.

When topping has thickened, pour at once into strainer. Press with back of spoon until only coarse residue remains. Discard residue. Gently stir lemon curd.

When shortbread is baked, remove from oven. Reduce temperature to 300 degrees (if using glass pan, keep temperature at 250 degrees).

Pour lemon curd on top of shortbread and bake 10 minutes longer. Let cool completely in pan on wire rack.

Refrigerate 30 minutes to set lemon curd completely.

Place powdered sugar in strainer; tap strainer with spoon to sprinkle a thick, even coating, covering lemon layer. Run a small metal spatula between sides of pan and pastry on 2 sides without foil. Use foil to lift out shortbread onto cutting surface.

Cut first into thirds with long, sharp knife. Then cut in half the other way and cut each half into thirds. Wipe blade after each cut.

Bars will keep 3 days at room temperature, 3 weeks refrigerated or 3 months frozen individually wrapped in plastic wrap.

Yield: 1 1/2 dozen bars.

Notes: Flour should not be packed into cup. To measure, stir well; dip measuring cup into flour, then push off excess with flat side of a knife.

Powdered sugar topping will be absorbed after several hours but can be reapplied before serving

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