Marbled Swiss Roll

This is a recipe to make a Swiss roll that is approximately 17" long. It can be cut into 20+ pieces to fill a party tray. 

Ingredients:

Cake flour  - 1 Cup

Egg - 8  

Sugar - 100g (~1/2 Cup)

Oil - 90g (~100ml)

Water - 80g (~80ml)

Salt -1g

Unsweetened hot coco powder - 2 TBSP

Optional: Strawberry jam for filling ( or choose other flavor )

Equipment:

Electrical mixer, oven, Half sheet cookie tray 13"x18", Parchment paper, mixing bowls(2), piping tip & bag

Steps:

1. Separate the eggs into egg yolk and egg white. 

2. In a mixing bowl, lightly beat egg yolk, oil, water, salt together. Then sift in the cake flour. Mix well until there is no lumps in egg yolk batter.

3. In an mixing bowl, add egg white, and sugar. Use a electrical mixer to beat it to soft peak.

4. Pour 1/3 of egg white foam into egg yolk batter. Gently fold with a spatula to mix them. 

5. Pour the egg yolk batter into the egg white bowl in a thin stream. Gently fold the batter into the egg whites. Use a spatula to cut down vertically through the mixture. Move the spatula across the bottom of the bowl; bring it back up the other side, carrying some of the mixture from the bottom over the surface. Repeat this process, rotating the bowl, until the ingredients are combined.

6. Preheat oven to 350°F.

7. Grease the cookie sheet with butter or oil, and line parchment paper on. 

8. Pour all batter, except 1/2 cup, on the cookie sheet. Use spatula to make the surface flat.

9. Add hot coco powder in the 1/2 cup batter left. Use piping bag to pipe it on the cake as straight lines. Then use a toothpick to draw across the batter which will form the marbled pattern.

10. Bake in oven for 20 minutes or until the surface is golden.

11. Take the cake out of the cookie tray, cool for 30 minutes.
12. Lay a new sheet of parchment paper on flat surface, coat the parchment paper with oil. This is to prevent the cake roll sticking to the paper. Put the cake upside down on the new parchment paper.

13. Remove the top layer parchment paper, and spread a thin layer of strawberry jam.

14. Roll the cake into a tight roll. Twist the paper on the end. Put the roll in refrigerator for 20 minutes.

15. Cut the roll into slices.

Here my swiss roll's skin was still sticky to the paper some. It may be because I did not brush the oil on parchment paper evenly, or I left it in refrigerator for too long before taken out to slice. I need some improvement there.