Pumpkin Sheet Cake

1 can (16oz) pumpkin
2 cups sugar
1 cup vegetable oil
4 eggs, lightly beaten
2 cups flour
2 tsp. baking soda
1 tsp ground cinnamon
1/2 tsp salt
1/3 tsp cloves

Frosting:
1 package (3oz) cream cheese, softened
5 tbsp butter or margarine softened
1 tsp vanilla extract
1 3/4 cups powdered sugar
3-4 tsp milk
optional: chopped nuts

Beat pumpkin, sugar and oil.  Add eggs; mix well.  Combine flour, baking soda, cinnamon, cloves and salt;  add to pumpkin mixture and beat until well blended.  Pour into a greased cookie sheet.  Bake at 350 for 25-30 minutes or until cake test done.  Cool. For frosting beat the cream cheese, butter, vanilla in a mixing bow until smooth.  Gradually add sugar; mix well.  Add milk until frosting reaches desired spreading consistency, frost cake.  Sprinkle with nuts.