Beat butter at medium speed with an electric mixer until creamy; gradually add brown sugar, beating well. Stir in egg and vanilla, beating well. Add dates; let stand 5 minutes. Combine flour, baking soda, baking powder, and salt. Beat butter mixture at high speed 3 minutes, gradually add flour mixture, beating well. Stir in semisweet chocolate morsels, chopped walnuts, and flaked coconut. Drop dough by rounded tablespoonful onto lightly greased baking sheets. Bake at 350~F for 10 to 12 minutes or until lightly browned. Note: Baked cookies may be frozen in airtight containers.