Beat together butter and sugar until creamy. Beat in egg yolks, then flour, salt, lemon rind and lemon juice. Spread stiff batter in ungreased 9-inch square pan. Bake in 350F oven 10 minutes. Beat egg whites until foamy. Beat in lemon juice. Gradually add sugar, beating constantly until very stiff. Fold in nuts. Spread topping evenly over crust. Return to oven and continue baking 25 minutes. Cool slightly. Cut into 16 squares. Bakes 16 bar cookies.
Updated: Monday, June 4, 2012.