Sift the cake flour at least twice.

Line a sheet cake pan with parchment paper.

Preheat the oven to 180°C (350°F).

In a bowl, combine egg whites and a pinch of granulated sugar.

Beat with a handheld mixer at low speed until white and thickened.

Add vanilla oil and the remaining granulated sugar in 2-3 batches, beating continuously.

Continue beating until stiff peaks form.

Add the sifted cake flour all at once.

Gently fold the flour into the egg white mixture using a rubber spatula, ensuring no lumps remain.

Be careful not to overmix the batter.

Pour the batter into the prepared pan and spread evenly to the corners.

Use a pastry scraper to level the batter.

Bake in the preheated oven for 10 minutes, or until lightly browned.

Remove from the oven and immediately cover the cake with a tightly wrung out, moistened kitchen towel.

Let the cake cool completely while still covered with the towel and parchment paper.

While the cake is cooling, prepare the whipped cream filling.

Combine heavy cream, granulated sugar, and vanilla essence in a bowl.

Whip until the cream is fairly stiff.

Wash and hull the strawberries.

Place a new sheet of parchment paper on your work surface.

Invert the cooled cake onto the new parchment paper and peel off the parchment paper it was baked on.

Spread the whipped cream filling evenly over the cake.

Arrange the strawberries in a line on top of the cream.

Spread the cream thinly on the edges of the cake, and more thickly where the strawberries are placed.

Roll the cake up firmly, starting from the end where the strawberries are.

Peel off the second parchment paper as you roll the cake.

Wrap the rolled cake tightly in plastic wrap.

Refrigerate for at least 1 hour to allow the cake to set.

For best results, chill overnight.

Before serving, trim the ends of the cake.

Heat a knife in hot water for a cleaner cut.

Slice and serve.