Heat oven to 350°F.
2. Combine 1 cup flour and 1/4 cup granulated sugar in medium bowl; cut in butter with two knives until mixture resembles coarse crumbs. Press mixture onto bottom of 9-inch square baking pan.
3. Bake 15 minutes or until lightly browned. Remove from oven; sprinkle white chips over top. Stir together eggs, lemon juice, lemon peel, remaining 1/4 cup flour and remaining 3/4 cup sugar in medium bowl; carefully pour over chips and crust.
4. Bake 15 minutes or until set. Cool slightly in pan on wire rack; sift powdered sugar over top. Cool completely in pan on wire rack; cut into bars. Makes 16 bars.