I’ll be honest Costco chocolate cake has been my guilty pleasure for years. Every bite of that dark, rich, creamy cake brings back celebrations, surprises, and sweet memories.
But I wanted something even better, something I could bake right in my kitchen and still get that same intense flavor.
After lots of trial and error, I finally nailed it. If you’ve ever craved that famous Costco chocolate cake, I promise—this homemade version hits the spot and then some.
Why Do Costco Cakes Taste So Good?
Costco cakes taste so good because they nail the texture and flavor balance every time. The cake layers are incredibly moist and tender, thanks to ingredients like oil and buttermilk. The chocolate flavor is bold but smooth—not too bitter, not too sweet.
What really pulls it all together is the rich frosting and creamy filling. It melts into the cake instead of just sitting on top.
Plus, everything is made fresh in large batches, so the consistency stays spot-on. I think it’s that combination of quality ingredients and perfect proportions that makes every slice so addictive.
How To Prepare Costco chocolate cake
⏱️ Quick Recipe Overview
- Preparation Time: 25 minutes
- Cooking Time: 35 minutes
- Total Time: 1 hour
- Course: Dessert
- Cuisine: American
- Yield: One 9-inch double-layer cake (Serves 10–12)
🧰 Equipment Needed
- Two 9-inch round cake pans
- Mixing bowls
- Whisk and spatula
- Stand mixer or hand mixer
- Cooling rack
- Offset spatula (for frosting)
- Saucepan (for ganache)
📝 Ingredients
For the Chocolate Cake:
- 1¾ cups all-purpose flour
- ¾ cup unsweetened cocoa powder
- 2 cups granulated sugar
- 1½ tsp baking powder
- 1½ tsp baking soda
- 1 tsp salt
- 2 eggs (room temperature)
- 1 cup buttermilk (room temperature)
- ½ cup vegetable oil
- 2 tsp vanilla extract
- 1 cup hot brewed coffee
For the Chocolate Mousse Filling:
- 1 cup heavy cream
- 1 cup semi-sweet chocolate chips
- 2 tbsp powdered sugar
For the Chocolate Ganache Frosting:
- 1½ cups heavy cream
- 1½ cups dark chocolate (chopped or chips)
- 1 tbsp unsalted butter
🍰 How TO Make Costco Chocolate Cake
Step 1: Prepare the Cake Pans
I greased the pans with butter and lined the bottoms with parchment paper. That way, the cake came out clean every time.
Step 2: Mix the Dry Ingredients
In a large bowl, I whisked together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Step 3: Add Wet Ingredients
I added the eggs, buttermilk, oil, and vanilla into the dry mixture. I beat everything until smooth. Then I slowly poured in the hot coffee while mixing. The batter looked thin, but that’s what makes the cake so moist.
Step 4: Bake the Cake
I poured the batter evenly into the pans and baked at 350°F (175°C) for 35 minutes. I tested the center with a toothpick—it came out clean. I let the cakes cool on a rack completely before frosting.
Step 5: Make the Mousse Filling
In a small saucepan, I heated the cream until it started to bubble. I poured it over the chocolate chips in a bowl, waited a minute, then stirred until smooth. Once cool, I whipped it with powdered sugar until light and fluffy.
Step 6: Assemble the Cake
I spread the mousse over one cake layer and topped it with the second layer. I chilled the cake while I made the ganache.
Step 7: Ganache Frosting
I heated the cream until just simmering, poured it over the chopped chocolate, and added butter. After letting it sit, I stirred until glossy. Once slightly cooled, I poured it over the cake and spread it smoothly with a spatula.
📊 Nutrition Facts (Per Serving)
- Calories: 470
- Fat: 30g
- Carbohydrates: 48g
- Sugar: 35g
- Protein: 5g
- Fiber: 3g
🍽️ Serving Suggestions
I love serving this cake with a scoop of vanilla ice cream or a drizzle of raspberry coulis. For a party, I like to top it with chocolate shavings or a few fresh berries. A cup of hot espresso or a cold glass of milk pairs perfectly.
How Can I Decorate A Costco-Style Chocolate Cake?
When I decorate a Costco-style chocolate cake at home, I like to keep it elegant but rich—just like the original. Here’s how I usually do it:
- Smooth Ganache Finish: I pour a glossy chocolate ganache over the top and gently let it drip down the sides. It gives the cake that sleek, signature look.
- Piped Chocolate Rosettes: Using a star tip, I pipe a few rosettes around the edge. I make them from the same mousse or ganache I use inside the cake.
- Chocolate Shavings or Curls: I use a vegetable peeler to shave a chocolate bar and sprinkle the curls over the top. It adds texture and drama.
- Fresh Berries or Gold Dust: Sometimes I top it with fresh raspberries or a light touch of edible gold dust for special occasions.
- Layered Borders: If I want a bakery finish, I pipe a border along the top and bottom edge of the cake using a closed star tip for that classic Costco-style trim.
I always chill the cake before decorating to make sure the frosting sets nicely. The key is to keep it rich, clean, and chocolate-forward.
💡 Tips and Variations
- Swap the Filling: I sometimes use whipped ganache or a Nutella mousse instead of regular chocolate mousse.
- Add Layers: Want a triple-layer cake? Double the recipe and go big.
- Gluten-Free Option: I’ve used a 1:1 gluten-free flour blend with great results.
- Make It Mini: Use cupcake tins and bake for 18–20 minutes for individual servings.
🍫 Health Benefits (Yes, Really!)
- Dark Chocolate: Rich in antioxidants that help reduce inflammation.
- Cocoa Powder: Improves brain function and supports heart health.
- Buttermilk: Low in fat but high in calcium and probiotics.
This isn’t health food, of course—but a slice now and then absolutely lifts my mood.
📝 Special Note
If you want that true Costco-style experience, let the cake chill in the fridge for a few hours before serving—but bring it back to room temperature about 30 minutes before slicing.
That’s when the mousse softens, the ganache gets glossy, and the flavors fully bloom. I never skip this step—it makes all the difference.
Also, if you’re baking ahead for a party, this cake holds up beautifully in the fridge for up to 3 days. Just keep it covered to lock in the moisture.
FAQ – Costco Chocolate Cake (Homemade Version)
Can I make this cake ahead of time?
Yes, I often bake the cake layers a day before and keep them wrapped at room temperature. I add the filling and frosting the next day. It actually tastes better after resting in the fridge overnight.
How do I store leftovers?
I cover the cake with plastic wrap or keep it in an airtight container in the fridge. It stays moist for up to 3–4 days. Before serving, I let it sit at room temperature for 20–30 minutes.
Can I freeze the cake?
Absolutely. I wrap the unfrosted cake layers in plastic wrap and foil, then freeze them for up to 2 months. When I need them, I thaw them overnight in the fridge and decorate fresh.
What can I use instead of buttermilk?
If I don’t have buttermilk, I make a quick substitute by mixing 1 cup of milk with 1 tablespoon of lemon juice or white vinegar. I let it sit for 10 minutes, then use it as a swap.
How do I keep the cake from drying out?
I make sure not to overbake it and always check with a toothpick around the 30-minute mark. I also wrap the cooled layers tightly in plastic wrap until I’m ready to assemble.
🔚 Conclusion
This homemade version of Costco chocolate cake recipe brings the same rich and moist experience right to your kitchen. With a deliciously chocolatey cake base and creamy frosting, it’s sure to be a hit at any occasion.
But now that I can make my own version at home—richer, deeper, and more personal—I don’t look back. Every time I bake this cake, I feel proud. It tastes like celebration, no matter the day.
If you try this recipe, I’d love to hear how it turned out for you. Let me know in the comments, or tag me if you share a photo. Happy baking!
Costco Chocolate Cake
Ingredients
Equipment
Method
- I greased the pans with butter and lined the bottoms with parchment paper. That way, the cake came out clean every time.
- In a large bowl, I whisked together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
- I added the eggs, buttermilk, oil, and vanilla into the dry mixture. I beat everything until smooth. Then I slowly poured in the hot coffee while mixing. The batter looked thin, but that’s what makes the cake so moist.
- I poured the batter evenly into the pans and baked at 350°F (175°C) for 35 minutes. I tested the center with a toothpick—it came out clean. I let the cakes cool on a rack completely before frosting.
- In a small saucepan, I heated the cream until it started to bubble. I poured it over the chocolate chips in a bowl, waited a minute, then stirred until smooth. Once cool, I whipped it with powdered sugar until light and fluffy.
- I spread the mousse over one cake layer and topped it with the second layer. I chilled the cake while I made the ganache.
- I heated the cream until just simmering, poured it over the chopped chocolate, and added butter. After letting it sit, I stirred until glossy. Once slightly cooled, I poured it over the cake and spread it smoothly with a spatula.