We have about 10 chocolate cakes in our repertoire, from Cynthia's Chocolate Cake made with cocoa and buttermilk, to the decadently rich Ballymaloe Chocolate Cake made with the very best chocolate money can buy, lots of ground almonds, and a silky chocolate frosting. But if I had to choose just one, it might have to be this recipe given to me by my sister Blathnaid Bergin. It is deliciously chocolatey, yet light and rich at the same time. You can serve it very simply with the chocolate ganache poured over the top or spruce it up for a birthday cake.