Beat eggs, canned pumpkin, sugar and lemon juice with electric mixer & set aside.
Mix together flour, cinnamon, nutmeg, baking powder, ginger & salt. Then fold into egg & sugar mixture. Spread into well greased and floured 15 x 10 x 1 inch pan. Sprinkle with 1 cup finely chopped walnuts. Bake at 375 for 15 minutes.
After cake cools slightly, very carefully lift out of pan and roll onto cotton (not terrycloth) towel that has been sprinkled with powered sugar. Starting at narrow end, or at wide end for larger cake, roll towel and cake together. Let cool. After cake is cool, unroll for filling.
Filling:
Beat powered sugar, cream cheese, butter and vanilla until smooth. Spread over cake than re-roll & chill. Freeze if you prefer and cut while still frozen into small slices.