Preheat oven to 375 degree.
Prepare 15 x 10 inch cake pan with vegetable shortening and flour.
2Sift together flour, baking powder, cinnamon, ginger, nutmeg, and salt and set aside.
Beat eggs 5 minutes with electric mixer until very thick.
Guadually add sugar.
Stir in pumpkin and lemon juice.
3Mix dry ingredients into pumpkin mixture and spread on a greased and floured 15 x 10 inch pan.
Sprinkle top with finely chopped nuts.
Bake 15 minutes at 375 degrees.
Loosen cake edges and turn out on a towel or wax paper, starting at narrow end, roll the cake and towel together.
Cool; unroll and add filling.
Combine all ingredients and spread over cake.
Roll again and sit on serving plate along seam, chill overnight before serving.
Dust cake with confectioners' sugar.