Spray a 15x10x1- inch baking pan* with nonstick cooking spray.
2In a large bowl, combine flour, sugar, baking powder, baking soda, cinnamon, nutmeg, salt, cloves, oil, eggs and pumpkin; beat at low speed for 30 seconds until moistened. Beat 2 minutes at medium speed. Stir in nuts and raisins.
3Pour into pan. Bake for 25 to 30 minutes or until toothpick inserted in center comes out clean. Cool completely
In a small bowl, combine butter, cream cheese, powdered sugar, milk and vanilla extract; beat until smooth.
Frost cooled bars. Store in refrigerator.
* To make Pumpkin Raisin Cake, use a 13x9-inch pan and bake for 40 to 50 minutes.