Preheat oven to 180° C.
Mix together flour, sugar, bicarbonate soda and baking powder.
In a separate bowl mix the milk, apple cider vinegar, oil and vanilla.
Combine wet and dry ingredients, mix well and then transfer half to another bowl. Add cocoa powder and extra milk to this half.
Dollop spoonfuls of mixture into cake tin, swirl for extra marble effect.
Bake for 45 minutes at 180° C, until a skewer comes out clean and leave to cool.
To make the icing combine butter, icing sugar and melted chocolate. Cover cooled cake in icing and leave to set before serving.

500 gram plain flour
200 gram sugar
2 teaspoon bicarbonate soda
2 teaspoon baking powder
400 ml plant milk of choice
2 teaspoon apple cider vinegar
250 ml vegetable oil
2 teaspoon vanilla
25 gram cocoa powder
50 ml plant milk
75 gram vegan butter of choice
100 gram icing sugar
100 gram dark vegan chocolate