Preheat oven to 350 F. Sift together flour, baking powder, soda and salt. Stir in pecans and half of chocolate chips and set aside. Combine softened butter, sugar, and brown sugar, beat well. Beat in egg and vanilla and then add flour/pecan mixture a little at a time, mixing well after reach addition. Spread in greased 9x13in pan. Sprinkle remaining half of chocolate chips over top. Bake at 350F for 20-25 minutes. Do not overbake Let cool in pan 30 minutes before cutting into 24 squares