To make the batter, preheat the oven to 350ºF (180ºC). Grease 3 loaf pans or 2 heart-shaped pans.
In a mixer, at high speed, beat together the eggs, sugar and vanilla for 10 minutes, until the mixture is light in color and thick, resembling a mousse consistency. Lower the mixer to the minimum speed and slowly drizzle in the oil while beating. Add the orange juice and water in the same way. Add the flour and baking powder, and beat slowly, until the batter is smooth. Put three-fourths of the batter into the pans.
To make the chocolate mixture, combine the melted chocolate and oil. Add the chocolate mixture to the remaining quarter of the batter and mix until combined. Spoon the chocolate batter over the white batter in the pans. Insert a knife in the batter, all the way through, and swirl to create the marble effect. Repeat in the other pan(s).
Bake for 40–45 minutes, until the cakes are springy and a toothpick inserted in their centers comes out almost dry. Let cool before serving.
Grandma Knows Best
Find another marble sponge—of the dense and buttery kind (in a good way)—on page 62.
Excerpted from Traditional Jewish Baking by Carine Goren (Page Street Publishing Co.: 2016)