Beat together 3 Eggs and 1 cup of sugar (5 min). Fold in the pumpkin and the lemon juice. Then fold in the flour, spices, salt, and baking powder. Pour into a greased and floured jelly roll pan or lipped cookie sheet and sprinkle with chopped nuts. Bake at 350? for 15 minutes. Dust a kitchen towel well with powdered sugar. Remove the cake roll from the pan and immediately place on sugared towel. Roll up cake in the towel and let cool. Unroll and spread filling on cake. Roll cake and filling into dessert roll. Chill and cut into 1/2 inch slices.