Japanese style chocolate cake roll made from a super soft and fluffy chiffon cake that melts in the mouth. Inside, it's filled with a light chocolate whipped cream. Airy and not overly sweet with all the chocolate goodness, it's so easy to indulge in the whole cake all by yourself!
Line a 8 X 12" rectangular cake pan with parchment paper.
In a small sauce pan, heat the milk and cocoa powder on medium heat until powder is fully dissolved. Do not let the milk come to a boil. Keep stirring continuously while breaking down big clumps of powder. Once fully dissolved, set chocolate milk mixture aside to cool.
In a large mixing bowl, add in sugar, baking soda, first portion of cream of tartar and salt. Sift in cake flour, stir to combine.
Create a well in the center. Inside it, add yolks, oil, vanilla extract and chocolate milk mixture.
Stir to combine until fully incorporated, do not over mix. Set this chocolate-flour mixture aside.
In a clean and dry, non-plastic mixing bowl, whip egg whites on slow speed until frothy, add second portion of cream of tartar. (Note 1)
Increase speed to med-high, whip until stiff peaks. You've now made a meringue. (Note 2)
Gently fold 1/3 of the meringue into the chocolate-flour mixture to get it moving. Once incorporated, fold in the rest of the meringue. Do not stir. Use batter immediately.
Dab a bit of the batter onto the sides of the parchment paper to keep corners together. Dab a little more onto the paper and stick it to the pan to prevent the parchment paper from tipping over into the cake batter.
Bake for 14-16 min. at 325F until a skewer pulls out clean and cake springs back in the center.
Place cooling rack over cake pan.
Flip cake over onto the rack, gently remove paper.
The side facing up will eventually become the top of the cake roll. Try to remove as much of the "skin" as possible since the cake will look better with exposed crumbs. Let it sit on cooling rack for 5 min.
Place a piece of new parchment paper on top
Place a mixing bowl and beaters in the freezer to chill. It will help the cream whip better.
Chop up chocolate into small pieces.
Place chocolate in a small pot along with the cream.
Heat over medium heat until chocolate is fully melted. Do not bring to a boil.
Let cool to room temperature then place in the fridge to chill. Check on it every 10-15 minutes and give it a gentle stir. It should be chilled before whipping but do not let it cool for too long as it will become too stiff to whip.
Place the chocolate and cream mixture in the chilled mixing bowl, then beat on low speed and slowly increasing to medium. Stop when it start to get stiff. Do not over whip.
Very carefully unroll the cake.
Gently add one even layer of the chocolate whipped cream onto the unrolled cake.
Very gently roll the cake back up using the parchment paper to help push the cake onto itself. This will help prevent cracking. To further prevent cracks, add more cream along the short edge that is folded first and do not try to roll the cake too tightly. Cut off the sides before placing on a presentation plate. Enjoy!