1. Preheat oven to 350ºF.
2. Combine cake mix, 1 egg and shortening in a large mixing bowl. Beat at low speed with electric mixer until crumbs form. Reserve 1 cup. Pat remaining mixture lightly into ungreased 13x9-inch pan.
3. Bake 15 minutes or until lightly browned.
4. Combine remaining 2 eggs, granulated sugar, lemon juice, lemon peel, baking powder and salt in medium mixing bowl. Beat at medium speed with electric mixer until light and foamy. Pour over hot crust. Sprinkle with reserved crumb mixture.
5. Bake 15 minutes or until lightly browned. Sprinkle with confectioners' sugar. Cool in pan. Cut into bars.