In a large bowl beat eggs for 2-3 minutes. Gradually add sugar until mixture is thick, approximately 2-3 minutes. Beat in water and vanilla
Combine the flour, baking powder and salt; fold into egg mixture
Spread batter into waxed paper lined 15 in. X 10 in. X 1 in. baking pan.
Bake cake at 375 degrees for 12-13 minutes.
Place cake on a confectioners sugar covered kitchen towel; gently peel off waxed paper.
Roll up cake in the towel in a jelly-roll style, starting with the short side. Allow to cool completely.
For the Filling:
Combine flour and milk in a small saucepan until smooth. Cook and allow mixture to come to a boil, stir for a minute longer ( mixture will be thick) and remove from heat. Transfer to a bowl and allow to cool.
In a large bowl. cream the butter, shortening and sugar until light and fluffy.
Beat in vanilla and salt.
Gradually beat in cooled milk mixture and beat until filling is light and fluffy.
Unroll the cake roll and spread mixture over the cake.
Roll up the cake again without the towel.
Place seam side down on a serving platter. Sprinkle with confectioners sugar. Place in refrigerator for 1 hour before serving.
Combine berries and sugar and allow to set for 30 minutes before serving.