I love those dark chocolate orange balls—year round, not just during the holidays. Since this cake already had the orange flavor built in all it needed was the chocolate. I subbed out 40 grams of the flour for unsweetened dark cocoa powder. The result is a subtle but rich chocolate flavor that would be right at home with some chocolate orange slices as a garnish. —Kim McMaster
Preheat oven to 350 and line and grease an 8x3 cake pan.
Combine all dry ingredients except espresso powder in a large bowl.
Dissolve espresso powder in milk. Combine espresso milk, olive oil, eggs, zest, juice and Grand Marnier in a separate bowl.
Add wet ingredients to dry and whisk until smooth. Pour battered into pan and bake for 1 hour or until cake tester comes out clean. Let cool in pan for half an hour before turning out onto cooling rack.