Cake : Grease a 15 x 10 inch jelly roll pan, line with waxed paper; grease paper.
Sift and measure flour with baking pwder.
Beat 4 eggs until foamy at high speed with electric mixer.
Gradually add sugar, vanilla and salt. Continue beating until mixture become thick and light in colour, about 5 minutes.
Carefully fold in flour mixture. Pour into prepared pan and bake at 400 for 12 - 15 minutes.
Immediately turn cake onto cloth sprinkled lightly with icing sugar. remove waxed paper. Trim edges. Starting with narrow end, roll cake in cloth.
Cool for 1 hour.
Filling and Frosting : Prepare 1 package Jello Pie filling as directed on package using 1 egg and reducing hot water to 1 1/2°C.
Chill 1 hour. Set aside approximately 1/2 C of pie filling. Unroll cake. Spread remaining pie filling evenly over cake; re-roll. Fold reserved pie filling into dessert topping. Frost cake ( or put a dollop on cake when serving). Chill.