1. Heat oven to 350°F. Lightly grease 13x9x2-inch baking pan. Combine sweetened condensed milk, lemon juice and lemon peel in medium bowl; set aside. Measure out 1/4 cup and 1/3 cup white chips; set aside. Add remaining white chips to lemon mixture.
2. Beat butter and brown sugar until blended in large mixer bowl. Stir together flour, oats, pecans, baking powder and salt; add to butter mixture, blending well. Remove 1-2/3 cups oats mixture; set aside. Add egg to remaining mixture, blending until crumbly. Press egg/crumb mixture on bottom of prepared pan. Gently spoon lemon mixture on top, spreading evenly. Add reserved 1/3 cup white chips to reserved crumb mixture. Sprinkle over lemon layer, pressing crumbs lightly.
3. Bake 20 to 25 minutes or until lightly browned. Cool in pan on wire rack. Place remaining 1/4 cup white chips and shortening in small microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds; stir. If necessary, microwave at MEDIUM 10 seconds at a time, stirring after each heating, until chips are melted and mixture is smooth when stirred. Drizzle over bars. Allow drizzle to set; cut into bars. Makes about 24 bars.
*To toast pecans: Heat oven to 350°F. Spread pecans in thin layer in shallow baking pan. Bake 7 to 8 minutes, stirring occasionally, until golden brown; cool.
WHITE CHIP LIME STREUSEL BARS: Make as directed above substituting lime for lemon.