Preheat oven to 350°. In a large bowl, cream butter and sugar until light and fluffy, 5-7 minutes. Beat in egg and vanilla. In a small bowl, whisk flour and baking powder; gradually add to creamed mixture, mixing well. Fold in coconut and walnuts., Press two-thirds of dough onto the bottom of a greased 13x9-in. baking pan. Spread with preserves; crumble remaining dough over preserves. Bake 30-35 minutes or until golden brown. Cool completely in pan on a wire rack. Cut into bars.