Combine butter and 1/4 cup brown sugar, creaming until light and fluffy. Add 1 cup flour, and mix well. Press mixture evenly into a lightly greased 9- inch square baking pan. Bake at 350° for 15 minutes.
Combine remaining sugar, flour, and baking powder in a large mixing bowl; stir in eggs and vanilla, mixing well. Add coconut and pecans; stir well.
Spread coconut mixture evenly over baked mixture. Bake at 350° for 25 minutes. Cool and cut into 2- x 1-inch bars.