Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) on the convection bake setting. Spray two large loaf pans with cooking spray.

Beat eggs and sugar in the bowl of

an electric mixer for several minutes,

until light and fluffy. Continue beating while slowly adding the oil, until it’s fully incorporated into the mixture.

In a separate bowl, mix the flours, baking powder, salt, and orange zest. In a third bowl, combine the milk, water, and vanilla extract.

Add the dry and wet ingredients

alternately to the bowl. Mix just until the dry ingredients are incorporated.

Melt chocolate in a double boiler.

Once chocolate is melted, set aside to

cool slightly. Using a spatula, mix two to three tablespoons cake batter into the melted chocolate. Once combined, fold in 1/3 of the cake

batter into the melted chocolate, until fully combined.

Divide the white batter between the

two pans. Then divide the chocolate

batter between the two pans, pouring

into the center or side of each pan. Using a toothpick or fork, partially mix the chocolate batter into the white batter to form a marble pattern.

Place the pans into the lower third of the oven and lower the temperature to 325 degrees Fahrenehit (160 degrees Celsius). Bake for 40–45 minutes, or until a toothpick inserted into the center comes out clean. Rotate the cakes at the 25-minute point so they bake evenly. Try

to avoid opening the oven door during the first 20 minutes.

Allow to cool, then cut into thick slices and enjoy! These cakes stay fresh for a few days at room temperature when wrapped in aluminum foil. They can be frozen too.