Preheat oven to 375 degrees. Spray 2 cookie sheets with non-stick cooking spray. In large bowl, with electric mixer at high, cream butter and sugar. Add egg, lemon juice and peel; beat until well- blended. In small bowl, stir together flour and baking powder. Stir into batter until just blended. Drop by rounded teaspoonfuls about 2 inches apart on cookie sheets. Bake 8-10 minutes until lightly browned. Remove to wire racks to cool.