Preheat oven to 350 F. Grease a 10x15 inch baking pan with cooking spray. Line it with parchment paper that extends a little bit up the sides of the pan. Spray the parchment paper with cooking spray.
Whisk together egg yolks and sugar until the mixture is lighter in color and a little frothy. Add the yolks, oil, milk and the matcha mixture. Stir well. Sift together cake flour and baking powder over the mixture. Stir well until smooth.
In the bowl of a stand mixer (or use a hand-held mixer), beat the egg whites until soft peaks form. Gradually add 1/4 cup of sugar, continuing to beat until stiff peaks form. Fold the meringue ( egg whites)* into the yolk batter using a rubber spatula in three additions. Incorporate well until the batter is uniform in color, Pour batter into the prepared pan and bake at 350 F for 10-12 minutes, or until the cake springs back to the touch. Slide the cake with the parchment paper onto a wire rack. Let it cool completely.
As the cake starts to cool, make the matcha whipped cream. Beat together whipping cream and powdered sugar until soft peaks form. Add the cooled matcha mixture and continue to beat until it is thick and fluffy.
Once the cake is cool, we need to remove the parchment paper backing. To do this, sprinkle a generous amount of powdered sugar* all over the cake. Cover the cake with a piece of parchment paper and top the parchment with a baking pan of the same size. Invert everything over.
Remove the pan on top and gently peel off the parchment paper. Reposition the parchment paper over the cake and top it with the baking pan again. Invert everything over once more so that the cake is facing side up again and is resting on an inverted baking pan. Remove the pan and the parchment paper on top.*
Spread the matcha whipped cream over the cake. With the short edge close to you, lift the parchment paper and start to roll the cake forward. Continue to roll, moving the parchment paper forward as you do, until you reach the other end.
Close the seams of the cake and press it along its body to reinforce the shape of the roll. Transfer the cake to a serving plate and gently unwrap it. Trim the edges of both ends of the roll, if desired to make the ends straight. Serve the cake in slices, chilled.