PREHEAT oven to 375° F.
COMBINE flour and powdered sugar in medium bowl. Cut in butter with pastry blender or 2 knives until mixture is crumbly. Press evenly onto the bottom of ungreased 13 x 9-inch baking pan.
BAKE for 10 to 12 minutes or until set.
SPRINKLE morsels and 1 cup chopped nuts over hot crust.
BEAT egg whites in medium mixer bowl until frothy. Gradually add brown sugar. Beat until stiff peaks form. Carefully spread meringue over morsels and nuts. Sprinkle with remaining nuts.
BAKE For 15 to 20 minutes or until golden brown. Serve warm or cool completely.