1Heat oven to 350°F. In medium bowl, mix Bisquick mix, 1/2 cup butter and 1/4 cup powdered sugar until blended. (Mixture will be crumbly.) Press in bottom of ungreased 8-inch square pan. Bake 20 minutes or until lightly browned.
2In medium bowl, mix granulated sugar, lemon peel, lemon juice, baking powder, salt and eggs with electric mixer on medium speed 3 minutes or until light and fluffy. Beat in melted butter. Pour over hot crust.
3Bake 25 to 26 minutes or until no indentation remains when touched lightly in center. Cool completely in pan on cooling rack, about 1 hour. Refrigerate 2 hours or until well chilled. Sprinkle with powdered sugar. Cut into 4 rows by 4 rows. Store covered in refrigerator.