Heat oven to 350°F. Spray 15x10x1-inch pan with cooking spray.
In large bowl, beat eggs, granulated sugar, oil and pumpkin with wire whisk until smooth. Stir in flour, baking powder, baking soda, salt, cinnamon, ginger and cloves. Stir in raisins. Spread in pan.
Bake 25 to 30 minutes or until toothpick inserted in center comes out clean and bars spring back when touched lightly in center. Cool completely, about 2 hours.
In medium bowl, beat cream cheese, butter, milk and vanilla with electric mixer on low speed until smooth. Gradually beat in powdered sugar, 1 cup at a time, on low speed until smooth and spreadable. Spreading frosting over bars. Sprinkle with walnuts. For bars, cut into 7 rows by 7 rows. Store covered in refrigerator.