Heat oven to 350F. Generously grease a 9x5-inch loaf pan. Combine flour, sugar, baking powder and salt; mix well. Combine egg, milk, oil and vanilla; blend well. Add to flour mixture; stir just until dry ingredients are moistened. Fold in 1 C. walnuts. Spoon into greased loaf pan. Sprinkle with remaining 1/3 C. walnuts. Bake at 350F for 1 hour or until toothpick inserted in center comes out clean. Cool in pan 10 minutes. Remove from pan and cool on wire rack. Makes 1 loaf.