Chop 1/2 cup walnuts fine. Grease 13 x 9 x 2-1/4-inch pan well. Sprinkle with walnuts to coat. Chop remaining walnuts a little more coarsely; set aside. Resift flour with baking powder and salt. Combine sugar, eggs, oil and spices. Beat at high speed until light and well mixed. Add half of flour mixture; stir until well blended. Add milk, then remaining flour. Stir in carrots and chopped walnuts. Pour batter in pan. Bake at 350 °F. for 40 to 45 minutes or until cake test done. Let stand in pan on wire rack 10 minutes. Turn cake out onto rack to cool. When cold, frost with a butter cream or cream cheese frosting. Decorate with walnuts halves.