Jelly Roll Blackbery Cake

.Jelly roll cake is sponge cake baked in a thin layer using the jellyroll cake pan. This basic jelly cake is super easy to make. This thin layer cake can then be filled with any kind of jam or ice cream to make a wonderful dessert to impress your friends. Blackberry is now in season here in the Pacific Northwest. Therefore, I will make this cake with blackberry jam.
Ingredients:
1/2 cup all-purpose flour sifted
1/2 tsp baking powder
pinch of salt
1/2 cup sugar
4 eggs separated
1/4 cup milk
1 tsp vanilla
1/3 cup blackberry jam

Icing:
1 1/2 cups powdered sugar
1/4 cup butter softened
1 tsp vanilla

Directions:
Pre heat oven to 375°
Grease a 15x10x1 inch jelly roll pan. Line with parchment paper and grease again. Set aside.
Divide sugar equally into two portions.
Sift flour, baking powder and salt.
With an electric mixer, whisk egg yolks and adding alternately the sugar and milk until achieving a pale yellow color. Add vanilla. Then sift flour into the whisked egg mixture.
In another clean bowl, with the electric mixer, whisk egg whites with sugar until stiff. Using a folding motion, fold the egg whites into the egg yolks. Pour the mixture into the prepared pan. Lift pan and tap lightly on countertop. Put in oven to bake for 8 to 10 minutes or until the cake is golden.
Sprinkle powdered sugar on a kitchen towel. Invert the cake, remove the parchment paper, and roll up.

 Let the cake cool off.
Unroll the cake. Spread the icing and blackberry jam, and then roll up again. Put plastic wrap around the jelly cake, and refrigerate for 7 hours or overnight before serving. Sprinkle more powdered sugar on top.