Cassis Biscuit Roulade

Before starting the recipe, I want to address my appreciation to Heather aka girlichef for giving me this special award. Thank you! Heather, for your support, your hard work and your friendship! (p.s. the drawings on the stamp means "Thank You" in Chinese.)
A Biscuit Roulade, or Jelly Roll, is a type of form cake, which baked in a sheet pan and then rolled around a filling, like whipped cream, jam, peanut butter, nutella, or ganache.

4 Eggs, large 4 tbsp Water, cool 125 g Sugar 1/3 tsp White vinegar / or lemon juice 90 g German #405 flour

50 g Cornstarch 3 g Baking powder 1 tsp Vanilla powder 3 tbsp Diet black currant marmaladeangiesrecipes

1. Line a 40 x 30 cm rectangular baking tray with baking paper and lightly butter the paper. In the large bowl of the standing mixer, whip the egg whites and water at medium speed until frothy. Add the white vinegar, increase the speed to high, and continue beating until the whites form soft peaks. Add sugar, 1 tablespoon at a time, whip until they form stiff peaks.
2. Fold in egg yolks, one by one, until blended. Gradually sift in the cake flour, cornstarch, baking powder and vanilla powder. Quickly but gently fold to combine. Pour into the prepared pan and bake at 200C /400F for about 14 minutes until golden on top.
   
   
3. Let the cake rest in the tray for 1 minute. Flip it out onto a clean tea towel that was sprinkled with powdered sugar. Brush the paper lining with water and let soak 1 minute before peeling it off the cake. Trim dry edges from the cake if needed. Roll the cake up tightly with the towel, rolling away from you and cool on a rack 30 minutes or more.
4. Carefully unroll the cake and spread it with a thin layer of black currant jam and tightly re-roll the cake and chill for at least 1 hour or up to 2 hours before slicing. With a wire cake leveler, gently slice the cake roll and serve.