PREHEAT oven to 350º F. Grease 13 x 9-inch baking pan.
COMBINE flour and sugar in large bowl. Cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Lightly press 2 1/2 cups crumb mixture onto bottom of prepared pan. Reserve remaining crumb mixture. Bake for 8 to 10 minutes or until light golden brown.
SPRINKLE 1 cup morsels and 1 cup nuts over hot crust. Drizzle evenly with sweetened condensed milk. Combine reserved crumb mixture with remaining morsels and nuts. Sprinkle over top of filling mixture. Press down lightly.
BAKE for 18 to 22 minutes or until edges are bubbly and top is golden brown. Cool completely in pan on wire rack. Cut into bars.