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If you’ve been on the hunt for a truly decadent, rich, and foolproof chocolate cake, look no further. This two-layer chocolate cake is moist, tender, and layered with the most luscious homemade chocolate buttercream frosting.

And here’s the best part—it’s made with a secret ingredient that guarantees a soft, melt-in-your-mouth crumb every single time: mayonnaise.

Now, don’t let that scare you off. Mayo is simply eggs and oil blended, which is exactly what every cake needs. It adds incredible moisture without making the cake heavy. Paired with a deep cocoa flavor and topped with creamy buttercream, this cake just might become your new go-to dessert for birthdays, celebrations, or those days when only chocolate will do.

Ingredients

For the Cake:

• 2 cups all-purpose flour
• 1 cup granulated sugar
• 1/2 cup light brown sugar
• 1/2 cup cocoa powder
• 1 tbsp baking soda
• Pinch of salt
• 1 cup mayonnaise
• 1 1/2 cups hot water or brewed coffee (for deeper flavor)
• 1 tsp vanilla extract
• 2 large eggs

For the Chocolate Buttercream:

• 1 cup (2 sticks) salted butter, softened
• 3 1/2 cups powdered sugar
• 3/4 cup unsweetened cocoa powder
• 1/3 cup heavy cream or milk (more if needed)
• 1 tsp vanilla extract
• Pinch of salt

Instructions

1. Prep

Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans. You can also just use these parchment paper sheets for quick removal.

2. Mix the Dry Ingredients

In a large bowl, whisk together the flour, both sugars, cocoa powder, baking soda, and salt.

3. Add the Wet Ingredients

Add mayonnaise, hot water or coffee, vanilla, and eggs to the dry mixture. Using a hand mixer or stand mixer, beat on medium speed until smooth (about 2 minutes). Don’t be alarmed—the batter will be thin, and that’s exactly how it should be.

4. Bake

Divide the batter evenly between the two pans. Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean. Allow cakes to cool in the pans for 10 minutes, then carefully turn them out onto wire racks to cool completely.

5. Make the Frosting

In a large mixing bowl, beat the butter until light and fluffy. Gradually add powdered sugar and cocoa powder, mixing well. Slowly beat in the cream, vanilla, and salt. Whip until the frosting is smooth, fluffy, and spreadable.

6. Assemble the Cake

Place one cake layer on a serving plate or cake stand. Spread a generous layer of frosting on top. Add the second cake layer, then frost the top and sides. Decorate with sprinkles, shaved chocolate, or keep it simple and rustic.

Tips for Success

• Coffee Boosts Flavor: Using hot brewed coffee instead of water deepens the chocolate flavor without making the cake taste like coffee.
• Cayenne Kick: Just a pinch adds warmth that complements the chocolate beautifully—no one will guess your secret.
• Make Ahead: Both the cake layers and frosting can be made a day ahead. Wrap cakes in plastic wrap once cooled, and store the frosting in the fridge. Let it come to room temperature before spreading.

This really is the best two-layer chocolate cake you’ll ever make—rich, soft, and absolutely irresistible. Serve it with a glass of cold milk, a hot cup of coffee, or a scoop of vanilla ice cream for the ultimate treat.

For more delicious cake inspiration, check out these cake recipes:

• Easy Strawberry Buttercream Cake
• How to Make a Boxed Cake Taste Like it Came From a Bakery
• Strawberry Cake Balls