4 eggs (around 55g each)
28g vegetable oil
52g cake flour
2g cocoa powder
5g lemon juice
5g vanilla extract
40g granulated sugar
120g heavy cream
- In a clean bowl, separate the eggs. Keep the egg white bowl cool in the fridge.
- In another bowl, mix well vegetable oil and milk until well combined. Add in cake flour and mix well. Add in egg yolks and mix well. Set aside.
- Preheat the oven to 338℉(170℃). Line the baking tray with parchment paper or baking mat.
- Take the egg white bowl out of the fridge; add in lemon juice, vanilla extract and sugar, and use a hand mixer to beat until it forms soft peaks. Take a scoop of whipped egg white and gently fold into the batter until just combined. Pour all the batter back into the whipped egg white, and gently fold it in until just combined.
- Save a scoop of batter, mix well with cocoa powder, and transfer into a piping bag. Pour rest of the batter into the baking tray and smooth it out. Pipe and draw the flower patterns. Send into the oven to bake for 25 minutes or until golden brown.
- Take the cake out of the oven, wait until cool to touch, release the cake from edges, turn the cake upside down, remove the baking tray, and peel off the baking mat.
- In a clean bowl, bring together heavy cream and sugar, and use a hand mixer to beat until thickened. Spread the whipped cream onto the side without flower patterns, smooth it out, and roll the cake up. Set the roll cake in the fridge to cool for 30 minutes. Slice and serve.