Chocolate Chip and Vanilla Marble Cake

I like making traybakes, and I discovered this recipe hidden amongst the bakes for children.
It was very straight forward and I liked the addition of chocolate chips to the chocolate mixture.
My only criticism would be the topping which is just plain and white chocolate. If I made it again, I would make the icing from the chocolate traybake, and streak it with white chocolate, and draw a knife through it to give the marbled effect on top.
It needed a drink with it, but it was very tasty. 8.0