Zebra cake

Ingredients:
250 ml vegetable oil
250 gr caster sugar
100 ml semi-skimmed milk
2 teaspoons vanilla
4 medium eggs
300 gr self-raising flour
1 tsp baking powder
25 gr cocoa powder
1 orange

Instructions:
Line a 23 cm cake tin and preheat the oven to 180 C. In a big bowl, add the first five ingredients and mix well to combine. Then, split this batter into two.
In the first bowl, make the vanilla batter by adding 175 gr self-raising flour and 1/2 teaspoon of baking powder. Mix it all together and set aside.
To the other bowl, add the cocoa powder, remaining 125 gr self-raising powder, 1/2 teaspoon of baking powder and orange zest to create the chocolate mix.
Now put each batter in piping bags, snip off the end and start building the cake. To begin, put a dollop of the vanilla batter in the centre of the cake tin. And then inside the vanilla batter, put the chocolate batter. Followed by the vanilla and the chocolate and so on… creating a target pattern. Though saying that, mine is a bit wonky as pictured below.
Bake the cake in the preheated oven for about 35 minutes. Let it cool slightly, cut into slices