Preheat your oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan or line it with parchment paper for easy removal.
2. Mix the Dry Ingredients
In a medium bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.
3. Cream the Butter and Sugar
In a large mixing bowl, beat the softened butter until creamy. Gradually add the sugar mixture and beat until light and fluffy.
4. Add the Eggs and Flavorings
Add the eggs one at a time, mixing well after each addition. Then, mix in the vanilla extract and orange zest until combined.
5. Combine the Wet and Dry Ingredients
Alternately add the buttermilk and the dry ingredient mixture to the butter mixture, starting and ending with the dry ingredients. Mix until just combined; be careful not to overmix.
If using, fold in the chocolate chips for extra chocolatey goodness.
6. Pour into the Pan
Pour the batter into the prepared loaf pan, spreading it evenly.
7. Bake the Cake
Bake in the preheated oven for 50-60 minutes, or until a toothpick inserted into the center comes out clean. The top should spring back when lightly touched.
8. Cool and Serve
Remove the loaf from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a cooling rack to cool completely before slicing.
Notes and Tips
Zesting the Orange: Use a microplane or fine grater to zest the orange, being careful to avoid the bitter white pith underneath the skin.
Storage: Store the cooled cake in an airtight container at room temperature for up to 3 days. You can also wrap it tightly in plastic wrap and freeze it for up to 2 months.
Serving Suggestions: Serve this loaf cake plain, dusted with powdered sugar, or with a dollop of whipped cream for an added treat.