Preheat oven to 350 degrees F and line a 8×4 loaf pan with parchment paper.

Prepare the orange cake batter by adding granulated sugar and orange zest, rubbing the zest into the sugar. Then add orange juice, olive oil, and milk, whisking until smooth.

Prepare the chocolate cake batter by adding milk, olive oil, and sugar, whisking until smooth. Then add the dry ingredients to this bowl and whisk until smooth.

Using a cookie scoop or spoon, add scoops of both batters into the loaf tray in alternating spots until batter is used up.

Using a knife or long toothpick, gently swirl the batter a bit to mix together.

Place loaf in oven on middle rack and bake for 40 – 45 minutes, checking for doneness with a toothpick at 40 minutes.

Remove from oven and let cool for 10 minutes in the pan, then remove and let finish cooling on a rack.

Prepare the ganache by adding milk to a microwave-safe bowl and microwaving for 30 seconds until warm. Add chocolate and stir until smooth.

Add ganache to the top of the cooled cake to serve.