PREHEAT oven to 350° F. Grease 13 x 9-inch baking pan.
COMBINE flour, sugar and walnuts in large bowl. Cut in butter and egg with pastry blender or two knives until mixture is crumbly. Reserve 1 1/2 cups of the crumb mixture. Press remaining crumb mixture into prepared pan. Spread marmalade evenly over crumb mixture in pan, leaving 1/2-inch border. Sprinkle white morsels and semi-sweet morsels evenly over the marmalade. Sprinkle reserved crumb mixture evenly over the morsels.
BAKE for 45 to 50 minutes or until top is light brown. Cool completely in pan on wire rack. Cut into bars.