Preheat oven to 350 degrees. Spray a sheet pan with baking spray and set aside.
In a mixing bowl, beat pumpkin, sugar, and oil. Add eggs, and mix well.
In another bowl, combine flour, baking soda, cinnamon and salt. Add these dry ingredients to the pumpkin mixture, and beat until well blended. Pour batter into prepared baking pan.
Bake for 25 to 30 minutes, or until cake tests done. Cool.
In a mixing bowl, beat the cream cheese, butter or margarine, and vanilla until smooth. Gradually add 1 3/4 cups confectioners' sugar, and mix well. Add milk until frosting reaches desired spreading consistency. Frost cake, and sprinkle with nuts.