Preheat oven to 400 degrees/ Lightly grease cookie sheets.
Sift flour with baking powder, soda and salt. In a large bowlbeat shorting and brown sugar untill light and fluffy. Beat in egg and vanilla. Add pinrapple. Mix well. Stir in flour mixture until well combined.
Drop by rounded teaspoonfuls spacing 2 inches apart ontp prepared cookie sheets. Bake 8 to 10 minutes or untill golden brown,(do not overbake) Transfer cookies to wire racks.
Mix confectioners sugar with 3-4 tablespoons reserved pineapple liquid to make glaze. Stir until smooth. Spread tops of warm cookies with glaze.