Decadent Chocolate Orange Cake with Zesty Orange Glaze

This easy chocolate orange cake is bursting with citrus and rich chocolate flavor. Moist and fudgy, it combines fresh orange juice, orange zest, and buttermilk for a bright, lively taste.

Topped with swirls of a silky chocolate-orange ganache and garnished with chocolate-dipped dried orange slices, this single-layer cake is elegant yet simple to prepare. Minimal fuss delivers maximum chocolate and citrus impact.

I was inspired to develop this chocolate orange cake after making a chocolate orange cheesecake earlier in the season. Instead of a multi-layer or highly involved cake, I focused on a single-layer version that is quick to assemble yet still rich in flavor. The cake base follows a dense, moist style with a fudgy crumb achieved by using a combination of Dutch-process cocoa and a touch of black cocoa for depth and dramatic color.

The bright citrus character comes from both orange zest and freshly squeezed orange juice, which are balanced by the tang and tenderness lent by buttermilk. The cake is finished with an easy ganache made by combining full-fat sour cream, finely grated orange zest, and high-percentage dark chocolate. The resulting frosting is glossy and spreadable, offering a fresh chocolate-and-citrus finish that complements the cake perfectly.

Ingredients

* See recipe card for precise measurements and conversions.

For the cake

• All-purpose flour
• Dutch-process cocoa powder (provides darker chocolate flavor; do not substitute with natural cocoa)
• Black cocoa powder (optional; deeply alkalized cocoa for dramatic color and cookie-like flavor; substitute with additional Dutch-process cocoa if unavailable)
• Kosher salt
• Baking powder
• Neutral vegetable oil (grapeseed, canola, or avocado oil)
• Granulated sugar
• Large eggs, at room temperature
• Buttermilk (adds tenderness and a subtle tang)
• Orange zest (from a navel orange)
• Vanilla extract
• Freshly squeezed orange juice (about 3 medium oranges)

For the chocolate-orange ganache

• Full-fat sour cream (creates a glossy ganache without cream)
• Finely grated orange zest
• Dark chocolate, chopped (50–72% cocoa recommended; 72% works well)

Decoration

• Dried orange slices dipped in dark chocolate (for a decorative, complementary garnish)

Substitutions and tips

Black cocoa powder enhances color and flavor but can be substituted 1:1 with Dutch-process cocoa if you don’t have it. For the ganache, full-fat Greek yogurt or crème fraîche can replace sour cream in equal measure if desired. Choose dark chocolate within the suggested range for balance — avoid bars that are excessively bitter.

Equipment

• 8-inch round cake pan (8 x 3 inches recommended)
• Small offset spatula or the back of a spoon for spreading ganache
• Mixing bowls, whisk, spatula, and a rack for cooling

Storage

Store the finished cake at room temperature for the first 2–3 hours. After that, keep it in an airtight container in the refrigerator for up to 3 days because the ganache contains sour cream. Bring the cake to room temperature before serving to restore the fudgy texture.

To freeze, wrap the cake tightly in plastic wrap and place it in an airtight container for up to 2 months. Thaw overnight in the refrigerator, then bring to room temperature before serving.

Recipe tips

• Allow the cake to cool completely before adding ganache. Warm ganache will run and may absorb into the crumb.
• Spread the ganache while it is still soft; it thickens and sets as it cools. If it becomes too firm, gently warm the bowl over a pan of hot water and stir until spreadable.
• Test the cake for doneness at about 40 minutes; a toothpick inserted into the center should come out with a few moist crumbs but not raw batter. Overbaking will dry the cake.

Recipe

Chocolate Orange Cake (one 8-inch layer)

Serves: 12 slices

Prep time: about 30 minutes. Bake time: 40–45 minutes. Cooling time: about 1 hour. Total time: around 2 hours.

Instructions — Cake

1. Preheat the oven to 350°F (177°C). Position a rack in the center of the oven.
2. Line the base of an 8 x 3 inch cake pan with parchment paper and grease the sides. Set aside.
3. Whisk together the dry ingredients: flour, Dutch-process cocoa, black cocoa (if using), salt, and baking powder. Set aside.
4. In a large bowl, whisk together the oil and granulated sugar until blended. Add the eggs one at a time, beating well between additions.
5. Stir in the buttermilk, orange zest, and vanilla extract until combined.
6. Add one-third of the dry ingredients and mix until incorporated. Add half of the orange juice and mix. Continue alternating the remaining dry ingredients and orange juice, ending with the dry ingredients. Whisk until smooth and evenly combined.
7. Pour batter into the prepared pan and smooth the top. Bake for 40–45 minutes, or until the top springs back when lightly touched and a toothpick inserted in the center comes out with just a few moist crumbs (not wet batter). Avoid overbaking.
8. Cool the cake in the pan for 10 minutes, then invert onto a wire rack to finish cooling completely before frosting.

Instructions — Chocolate Orange Ganache

1. Place the sour cream in a mixing bowl and add the finely grated orange zest. Whisk to combine and set aside while you melt the chocolate.
2. Gently melt the chopped dark chocolate in short bursts in the microwave, stirring between each burst, until smooth. Alternatively, use a double boiler.
3. Pour the melted chocolate into the sour cream and orange mixture. Whisk gently until fully incorporated and glossy. Scrape the sides and bottom of the bowl to ensure even mixing.
4. Scoop the ganache onto the cooled cake and spread to the edges with a mini offset spatula or the back of a spoon, creating gentle swirls. Garnish with chocolate-dipped dried orange slices.

Notes

Cake: This cake is intentionally moist and fudgy. Expect a slightly dense crumb that remains tender. If you skip black cocoa, use additional Dutch-process cocoa for color and intensity. Oven temperatures vary, so begin checking for doneness at 40 minutes.

Ganache: Work while the ganache is still soft for easiest spreading; it will firm as it cools. If it becomes too thick before you spread it, warm the bowl briefly over hot water and stir until it reaches a spreadable consistency.