In a bowl, beat the eggs, sugar, oil and pumpkin until well blended. Combine the flour, cinnamon, baking powder, baking soda and salt; gradually add to pumpkin mixture and mix well. Pour into an ungreased 15-in. x 10-in. x 1-in. baking pan. Bake at 350° for 25-30 minutes or until set. Cool completely.
For icing, beat the cream cheese, confectioners' sugar, butter and vanilla in a small bowl. Add enough milk to achieve spreading consistency. Spread over bars. Store in the refrigerator.