1. Sift flour, soda, pumpkin pie spice, and salt onto wax paper.
2. Beat butter or margarine with brown sugar until fluffy in large bowl with an electric mixer at high speed; beat in egg, mashed bananas and vanilla. Stir in flour mixture, half at a time, until well blended; stir in dates. Drop by rounded teaspoonfuls onto lightly greased cookie sheets.
3. Bake in moderate oven (375°) 10 minutes, or until firm and lightly goldeni around edges. Remove from cookie: sheets to wire racks; cool.