Heat oven to 350. In 8 inch square baking pan combine flour, sugar, baking powder and salt. In small bowl, with wire whisk, stir together egg and vanilla. Make 2 indentations in flour mixture; pour oil in one and egg mixture in other. Add milk; stir until well mixed. Stir in pecans. Bake for 30 to 40 minutes or until wooden pick inserted in center comes out clean. Sprinkle chocolate chips on warm cake. Let stand 2 minutes; slightly swirl melted chips.