Rinse apricots; cover with water; boil 10 minutes. Drain, cool, chop.
Mix butter, sugar and 1 cup flour until crumbly. Pack into greased and floured 8 inch square pan.
Bake at 350 degrees for 20 minutes or until lightly browned.
Sift 1/3 cup flour, baking powder and salt.
In a large bowl, with mixer at low speed, gradually beat brown sugar into eggs; mix in flour mixture, then vanilla.
Stir in walnuts and apricots. Spread over baked layer.
Bake 30 minutes more or until done; cool in pan.
If desired, dust with powdered sugar.