Sponge Cake Roll with Custard

Beat room-temperature eggs with salt, sugar, and vanilla in a bowl for about 10 minutes until pale and fluffy.

Gently fold in the sifted flour with baking powder in 3-4 additions, stirring carefully from bottom to top.

Once the flour is well incorporated, pour in the vegetable oil and warm milk, and gently mix.

Transfer a couple of tablespoons of the batter into a small bowl, add 1 tsp of cocoa powder, and mix.

Spread the light batter onto a baking sheet lined with parchment paper, drop spoonfuls of the chocolate batter randomly on top, and use a wooden skewer to create a pattern.

Bake in a preheated oven at 180°C (350°F) for about 15 minutes.

While still hot, roll it up tightly in a kitchen towel.