Description

This luscious Chocolate Orange Cake combines rich cocoa with the bright, zesty flavor of fresh navel orange. Soft and tender with a moist crumb, it’s baked to perfection and topped with a creamy chocolate orange frosting that’s both decadent and refreshing. Perfect for any occasion, this cake cleverly balances the deep chocolate notes with citrus brightness in every bite.

Ingredients

Scale

Cake

6 tablespoons (85 grams) butter, at room temperature
3/4 cup (145 grams) brown sugar
2 tablespoons (25 grams) white sugar
1 large egg + 1 egg yolk
Zest of half a large navel orange (~1 teaspoon)
1 cup (130 grams) flour
1/2 cup (40 grams) cocoa powder
3/4 teaspoon baking powder
1/4 teaspoon baking soda
1/2 teaspoon fine sea salt
3/4 cup whole milk
1/2 teaspoon white vinegar

Chocolate Orange Frosting

8 tablespoons (1 stick; 113 grams) unsalted butter, softened
1/2 teaspoon fresh navel orange zest
1 tablespoon fresh orange juice
1/2 cup (40 grams) cocoa powder
1 1/2 cups (168 grams) powdered sugar
2 ounces semisweet chocolate, melted and slightly cooled (optional)

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Instructions

Preheat and Prepare Pan: Preheat your oven to 350°F (175°C) and lightly spray an 8-inch square or round pan with non-stick cooking spray to prevent sticking.
Cream Butter and Sugars: In a large bowl, beat together the room-temperature butter, brown sugar, and white sugar until the mixture is creamy and smooth, approximately 1 minute.
Add Eggs and Orange Zest: Incorporate the whole egg, egg yolk, and orange zest into the butter mixture. Beat until all are well combined.
Combine Dry Ingredients: Evenly sprinkle the flour, cocoa powder, baking powder, baking soda, and sea salt over the wet ingredients. Beat briefly to start blending the mixture.
Mix Milk and Vinegar: Stir together the whole milk and white vinegar in a separate cup. Add this liquid mixture to the batter and beat just until all ingredients are fully combined without overmixing.
Bake the Cake: Pour the batter into the prepared pan and bake for 20-22 minutes. Check doneness by inserting a toothpick in the center; it should come out clean. Do not underbake to prevent sinking. Allow the cake to cool completely in the pan.
Prepare the Frosting: To make the chocolate orange frosting, combine softened unsalted butter, fresh orange zest, orange juice, cocoa powder, and powdered sugar in a bowl. Beat with an electric mixer for a few seconds until combined.
Add Melted Chocolate: Stir in the melted and slightly cooled semisweet chocolate (optional) and continue beating until the frosting becomes soft and creamy.
Frost and Serve: Spread the frosting evenly over the cooled cake. Garnish with extra orange zest if desired and serve to enjoy this delightful chocolate orange treat.

Notes

Cake Pans: Use either an 8-inch round or square pan. If using a 9-inch round pan, bake a few minutes less as it will cook faster.
Brown Sugar: Both light and dark brown sugar variations work well in this recipe.
Eggs: Use one whole egg plus one egg yolk; save the leftover egg white for another use.
Orange: One large navel orange provides enough zest and juice for both cake and frosting.
Milk: Whole milk is preferred for the cake’s tender crumb; avoid dairy alternatives lacking protein for best results.
Vinegar: Essential for leavening reaction with baking soda and powder; white, apple cider, or rice wine vinegar work fine.
Semisweet Chocolate: Adding melted chocolate to the frosting makes it richer but is optional based on preference.

Nutrition

Serving Size: 1 slice (approx. 1/9 of cake)
Calories: 350 kcal
Sugar: 30 g
Sodium: 250 mg
Fat: 18 g
Saturated Fat: 11 g
Unsaturated Fat: 6 g
Trans Fat: 0.2 g
Carbohydrates: 42 g
Fiber: 4 g
Protein: 5 g
Cholesterol: 85 mg