A marble cake is a cake with a streaked or mottled appearance (like marble) achieved by very lightly blending light and dark batter.It can be a mixture of vanilla and chocolate cake, in which case it is mainly vanilla, with streaks of chocolate. https://en.wikipedia.org/wiki/Marble_cake
Ingredients
5 large eggs
250g granulated sugar
250g butter
250g all-purpose white flour
1 teaspoon vanilla extract
Pinch of salt
1 teaspoon baking powder
2 tables spoon cocoa powder
First step
Sift the dry ingredients together 3 times.(flour, baking powder)
Divide the mix into two even portions.
Add cocoa powder to one portion and mix well.
Keep it a side.
Second step
Preheat oven to 180ºC.
Cream the margarine/Butter and sugar together.
Then add the eggs one at a time, beating well after each one.
Add vanilla.
Third step
Divide the mix into two even portions.
Add cocoa mixed flour in to one portion, and leave the second plain.
Place spoonfuls of each mixture into the tin and use the end of a knife to marble together. Take care not to over mix.
Drop the tin gently onto the kitchen bench to eliminate air bubbles.
Bake at 360 F / 180 C for about 45 minutes,
Until it will become golden brown, and when you press the top of the cake it feels firm. Or cook until a toothpick inserted in the center comes out clean.
Let the cake cool in the pans 10 minutes then turn out.