Preheat the oven to 165℃. Grease the Swiss Roll pan 15" x 9" by butter and line with a sheet of parchment paper.
Chill a metal mixing bowl in the fridge to cool for preparing the filling later.
In two separate bowls, separate the egg whites and the egg yolks. Be careful, do not mix any egg yolks into the egg whites.
In another mixing bowl, whisk the egg yolks and 45g of sugar until thicken in texture.
Add pure vanilla extract, milk and vegetable oil to the egg mixture and mix them well.
Add the sifted sesame powder, all-purpose flour and cornstarch to the egg mixture and mix them well.
In the stand mixer, whisk the egg whites until foamy at low speed. Add the cream of tartar. Then add the sugar spoonful by spoonful. After that, continue to beat the egg whites at high speed until stiff peak form. It takes around 6-8 minutes.
Use a spatula to add a little of egg white into the egg yolk mixture to loosen up the texture.
Fold the egg white into the mixture gently until all well combined in 3 portions. Be gentle and be patient at this stage, you do not want to beat all the air out.
Pour the batter into the prepared pan and use an offset spatula to spread into an even layer. Bake it for around 13-15 minutes, until top springs back when lightly pressed.
Prepare a sheet of parchment paper, spread it onto a flat surface. Invert the warm cake onto the parchment paper. Peel off the baked parchment paper. Use a sharp knife to cut the edges to make it look neat.
Starting at the short side, use the parchment paper to tightly roll the cake. Let it cool completely on a wire rack.
Make the filling, take the chilled mixing bowl out from the fridge. Whisk together double cream, powdered sugar, pure vanilla extract, and salt, until stiff peak form. Refrigerate it until ready to use.
When the cake is cool, unroll it and spread the filling evenly over the cake. Leave around 1 cm at the end. Roll the cake back into a roll, this time without the parchment paper. Place the seam side down on a serving plate and refrigerate it until well chilled, 1 hour.
Decorate the Swiss Roll by piping the rest of the filling and sprinkle some black sesame seeds on top. (Optional)
Cut a slice and have it with a cup of tea! Delicious! Happy Baking!