Preppy Kitchen Mocha Cake

This is John Kanell’s mocha cake from Preppy Kitchen, made for my mom’s birthday. Three layers of deep coffee-bloomed chocolate cake, a mocha buttercream that tastes like a good latte, and a dark chocolate ganache that goes between the layers and drips down the sides. The vegetable oil keeps it soft even straight from the fridge, which is where this cake lives.

Makes one 3-layer 9-inch cake.

Ingredients

Cake layers

• 1/2 cup (40 g) Dutch-processed cocoa powder
• 1 cup hot coffee, freshly brewed
• 3 cups (360 g) plain flour
• 2 1/2 cups (500 g) granulated sugar
• 2 1/2 tsp baking soda
• 1 1/2 tsp baking powder
• 1 tsp salt
• 1 cup vegetable oil
• 1 cup buttermilk
• 3 large eggs, at room temperature
• 1 tbsp vanilla extract

Mocha buttercream

• 7 1/2 cups (900 g) powdered sugar, sifted
• 1 tbsp cocoa powder
• 1 tbsp instant espresso powder
• 2 cups (4 sticks) unsalted butter, at room temperature
• 1/2 tsp salt
• 3 tbsp heavy cream
• 1 tbsp vanilla extract

Chocolate ganache (between layers + drip)

• 1/2 cup (90 g) dark chocolate, chips or chopped bar
• 1/4 cup heavy cream

To finish

• chocolate-covered espresso beans, some chopped (optional)

Method

Cake

1. Prep. Heat the oven to 350 °F (175 °C). Grease three 9-inch cake pans and line the bottoms with parchment rounds.
2. Bloom the cocoa. Whisk the 1/2 cup cocoa with the 1 cup hot coffee until smooth and lump-free, then set aside to cool for 10 minutes. Blooming the cocoa in hot liquid pulls out a deeper chocolate flavour.
3. Dry ingredients. In a large bowl, whisk together the flour, sugar, baking soda, baking powder and salt.
4. Wet ingredients. To the cooled cocoa-coffee mixture, add the oil, buttermilk, eggs and vanilla, and whisk until combined.
5. Combine. Pour the wet into the dry and whisk until just combined — don’t overmix, or you’ll work up the gluten and end up with a dense, gummy crumb.
6. Fill the pans. Divide the batter evenly between the three pans. A scale helps here if you want even layers.
7. Cake strips (recommended). Soak fabric cake strips in water, squeeze out the excess, and wrap one around each pan. They insulate the edges so the layers bake flat and stay soft all the way through.
8. Bake at 350 °F for about 30 minutes. If you’re using multiple racks, rotate the pans after 20 minutes. Cool in the pans for a few minutes, then turn out onto wire racks to cool completely.

Mocha buttercream

1. Sift together the powdered sugar, cocoa and instant espresso. Set aside.
2. In a stand mixer with the paddle, cream the room-temp butter on medium for about 5 minutes, until pale, light and fluffy.
3. Drop to low and add the sifted sugar mixture one cup at a time, scraping down the bowl often.
4. Add the salt, heavy cream and vanilla, and mix until smooth and creamy.

Chocolate ganache

1. Put the chopped chocolate in a small heatproof bowl.
2. Microwave the heavy cream for 20–30 seconds, until steaming.
3. Pour the cream over the chocolate, let it sit 2–3 minutes, then whisk smooth. If it isn’t fully melted, microwave 20 seconds at half power, stir, and repeat.

Assembly

1. Set the first layer on a plate or turntable. Spread about 1 cup of frosting over it.
2. Drizzle over about 1 tbsp of ganache and spread it lightly, then scatter half the chopped espresso beans, if using.
3. Repeat with the second layer, then top with the third.
4. Apply a thin crumb coat all over the cake and chill 10–20 minutes to set.
5. Frost the sides with a final coat, reserving some buttercream for piping.
6. Pour or pipe ganache over the top, letting it drip down the sides. Chill another 10–20 minutes to set the drip.
7. Fit a piping bag with a closed star tip and pipe dollops around the top edge. Top each dollop with a chocolate-covered espresso bean.
8. Refrigerate at least 20 minutes before slicing.

Notes

• No instant espresso? Brew a double shot, cool it, and add it to the buttercream instead.
• Natural vs. Dutch-process cocoa: either works. Dutch is darker and reads more fudgy.
• Cake strips genuinely make a difference — flat, evenly soft layers. Worth the extra step.
• Less sugar = less sweet but more bready. Sugar is also a tenderiser, so cutting it changes the texture, not just the sweetness.
• This cake keeps in the fridge and stays soft cold, thanks to the oil.

Happy birthday, Mom! 🎂