Slit the dates (about 8 ozs worth) and stuff with pecan halves; set aside. In saucepan melt butter or margarine and stir in brown sugar until well blended. Remove from heat; cool to lukewarm. Blend in sour cream, eggs, and vanilla; mix thoroughly. Stir together the flour, baking powder, baking soda, salt and ginger. Add to sour cream mixture; mix well. Pour into a greased 13 X 9 X 2-inch baking pan. Carefully arrange stuffed dates atop batter in lengthwise rows with 6 stuffed dates in each row. Bake at 350 degrees F. for 25 to 30 minutes. Cool; cut into bars, allowing 1 date per par. Sift powdered sugar over the top if desired. Makes 30 bars.