In a mixing bowl, beat pumpkin, 2 cups white sugar and oil. Add eggs, and mix well.
In another bowl, combine flour, bicarb soda, cinnamon and salt. Add these dry ingredients to the pumpkin mixture and beat until well blended. Pour batter into a 20x30cm baking pan.
Bake at 180 degrees C 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 icing sugar and mix well. Add milk until icing reaches desired spreading consistency. Ice cake and sprinkle with nuts.