Cream butter and sugar until fluffy. Add eggs, one at a time, beating throughly after each. Add vanilla. Mix flour, baking powder and salt. Add to creamed mixture with about half the syrup. Blend well. Stir in remaining syrup and nuts. Turn into greased 13x9 inch baking pan. Bake at 350F for 35 min or until pick inserted near center comes out clean. Cool in pan or wire rack. To serve, cut in squares. Serve plain, with ice cream or with toppings, if used.