Matcha Cake Sheet
1-Preheat oven to 350°F: Preheat oven to 350°F. Line a 12×17″ baking tray with parchment paper cut to size and set aside.
2-In a small bowl, stir together flour,: In a small bowl, stir together flour, matcha powder (sift it in if clumpy), and baking powder. Set aside.
3-Separate the egg whites and egg yolks: Separate the egg whites and egg yolks into two large mixing bowls, being careful not to get any yolk in the egg whites. Set the bowl of egg yolks aside.
4-To the egg whites, add cream of: To the egg whites, add cream of tartar. Use an electric hand mixer to beat the egg whites on low-medium speed until they become frothy like cappuccino foam. Add 100g of sugar, one spoonful at a time, mixing in between each addition. After all the sugar has been added, continue beating on medium-high speed until the meringue becomes stiff peaks. Set aside.
5-To the egg yolks, add the remaining: To the egg yolks, add the remaining 50g of sugar. Use the same hand mixer to mix until combined. Add the milk, oil, and vanilla extract and mix until combined. Use a fine mesh sieve to sift the flour mixture into the egg yolk mixture. Mix on low speed until the flour has just combined.
6-Add about ⅓ of the egg white: Add about ⅓ of the egg white meringue into the egg yolk mixture and fold together with a spatula, making sure to scrape the bottom of the bowl. Add the rest of the meringue and fold together until no streaks remain. Again, make sure to scrape the bottom and sides of the bowl where thicker batter can stick. Don’t overmix.
7-Pour the batter into your lined baking: Pour the batter into your lined baking tray. Use an offset spatula to spread the batter into the corners and edges of the pan and smooth the batter into an even layer.
8-Bake for 12-15 minutes or until the: Bake for 12-15 minutes or until the edges are lightly browned and the top of the cake sheet is puffed up.
9-Let the cake cool on a wire: Let the cake cool on a wire rack for only about 5 minutes before running an offset spatula around the edges of the pan to release the cake. Place a wire rack on top of the pan, grip both sides of the pan and rack (with oven mitts), and flip the cake onto the rack. Peel the parchment paper off the cake. Place a fresh sheet of parchment paper on top and flip the cake onto the parchment paper.
10-Cut the browned edges off the two: Cut the browned edges off the two short ends of the cake sheet. While the cake is still warm, roll the cake up with the parchment paper starting from a short end. Let the cake cool completely in this rolled-up log shape.

Matcha Whipped Cream Filling
11-In a large mixing bowl, sift in: In a large mixing bowl, sift in the matcha powder and add a small amount of whipping cream. Use a spatula to mix them together, smearing the matcha powder against the bottom and sides of the bowl to get rid of the clumps.
12-Add the rest of the whipping cream,: Add the rest of the whipping cream, powdered sugar, and vanilla extract. Use an electric hand mixer to beat until it becomes stiff peaks.
13-Unroll your cooled cake sheet: Unroll your cooled cake sheet. Add dollops of whipped cream on top of cake. Use an offset spatula to spread the cream into a thick, even layer. Leave the last 2″ at the end of the cake sheet empty. Save any remaining whipped cream for decoration later.
14-Roll the cake up in the same: Roll the cake up in the same way as before. When you get to the end of the roll, place a sheet of plastic wrap next to the cake so that you can roll the cake right onto the plastic wrap. Use an offset spatula to remove any excess cream that squishes out of the seam and push any cream that comes out from the two ends of the roll. Wrap the cake roll in plastic wrap and chill in the fridge for at least 3 hours or overnight to allow the cream to set.
15-Before serving, use a serrated knife to: Before serving, use a serrated knife to cut off about ½” off both ends of the roll to reveal the swirl. Cut the cake into 1-1.5″ slices and pipe any remaining whipped cream on top (optional).