Moist Chocolate Layer Cake with Chocolate Buttercream

Name: Moist Chocolate Layer Cake with Chocolate Buttercream
Prep time: 1 h
Cook time: 32 min
Total time: 1 h 32 min
Yield: 12 servings
Cuisine: American
Ingredients: 2½ cups (300 g) all-purpose flour, spooned into the cup and leveled; 2 cups (400 g) granulated sugar; 1 cup (90 g) natural unsweetened cocoa powder, sifted if lumpy; 1½ tsp (7 g) baking soda; 1 tsp (4 g) baking powder; 1 tsp (6 g) fine salt; 3 whole (150 g) large eggs, at room temperature; 1 cup (240 ml) buttermilk, at room temperature, shaken; ½ cup (120 ml) neutral vegetable oil; 2 tsp (10 ml) pure vanilla extract; 1 cup (240 ml) hot brewed coffee, freshly brewed, steaming hot; 1 tbsp (14 g) unsalted butter, softened, for greasing the pans; 4 oz (113 g) semisweet or bittersweet chocolate (55–65%), finely chopped; 1½ cups (3 sticks) (340 g) unsalted butter, softened to cool room temperature (about 65°F/18°C); 3½ cups (420 g) powdered sugar, sifted; ¾ cup (65 g) unsweetened cocoa powder, sifted; ¼ tsp (1½ g) fine salt; 6 tbsp (90 ml) heavy cream, at room temperature, plus more if needed; 2 tsp (10 ml) pure vanilla extract

From the MyKitchenBank Kitchen

A deeply chocolatey two-layer cake with a tender, moist crumb from buttermilk and hot coffee, covered in silky, fudgy chocolate buttercream. The batter comes together in one bowl with no mixer, and the frosting is rich without being gritty.

Prep: 1 hr
Cook: 32 min
Wait: 1 hr 35 min
Total: 3 hr 7 min
Makes: 1 double-layer 9-inch cake (12 slices)

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Ingredients

12 servings

For the cake
2½ cups (300 g) all-purpose flour, spooned into the cup and leveled
2 cups (400 g) granulated sugar
1 cup (90 g) natural unsweetened cocoa powder, sifted if lumpy
1½ tsp (7 g) baking soda
1 tsp (4 g) baking powder
1 tsp (6 g) fine salt
3 whole (150 g) large eggs, at room temperature
1 cup (240 ml) buttermilk, at room temperature, shaken
½ cup (120 ml) neutral vegetable oil
2 tsp (10 ml) pure vanilla extract
1 cup (240 ml) hot brewed coffee, freshly brewed, steaming hot
1 tbsp (14 g) unsalted butter, softened, for greasing the pans
For the buttercream
4 oz (113 g) semisweet or bittersweet chocolate (55–65%), finely chopped
1½ cups (3 sticks) (340 g) unsalted butter, softened to cool room temperature (about 65°F/18°C)
3½ cups (420 g) powdered sugar, sifted
¾ cup (65 g) unsweetened cocoa powder, sifted
¼ tsp (1.5 g) fine salt
6 tbsp (90 ml) heavy cream, at room temperature, plus more if needed
2 tsp (10 ml) pure vanilla extract

Equipment (9)

Two 9-inch (23 cm) round cake pans, at least 2 inches (5 cm) deep
Parchment paper
Large mixing bowl and whisk
Stand mixer with paddle attachment or hand mixer
Fine-mesh sieve
Wire cooling racks
Small heatproof bowl and saucepan (or microwave) for melting chocolate
Serrated knife, offset spatula and cake turntable or flat plate
Instant-read or toothpick for testing

Steps

Before you start

Take the eggs, buttermilk and the frosting butter out of the fridge about 1 hour ahead. The butter should dent easily when pressed but not look shiny or greasy (about 65°F/18°C).
Brew the coffee just before mixing. It needs to be hot for the cocoa to bloom, and the batter will be very thin. That is correct.
Use natural (non-alkalized) unsweetened cocoa in the cake. The baking soda needs its acidity to rise properly. Dutch-process cocoa works well in the frosting if you prefer.
Plan on about 3 hours 10 minutes total. The layers must be completely cool before frosting, or the buttercream will melt.

1
Prep oven and pansOven 350°F / 175°C
- Position a rack in the center of the oven and heat to 350°F (175°C).
- Grease the bottom and sides of two 9-inch (23 cm) round pans with the 1 tablespoon softened butter.
- Trace and cut a parchment round for each pan, press it into the bottom, and grease the parchment lightly.
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Ready when: Pans are fully coated with no bare spots and parchment lies flat.
Tip: Parchment is essential for chocolate cakes, which tend to stick to the bottom.
2
Whisk dry ingredients
- In a large bowl, whisk the flour, sugar, cocoa, baking soda, baking powder and 1 teaspoon salt for 30 seconds until evenly colored with no streaks or cocoa lumps.
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Ready when: The mixture is a uniform dark brown with no pale streaks.
Tip: Press any cocoa lumps against the side of the bowl with a spoon or sift them out.
3
Mix wet ingredients
- In a large measuring cup or second bowl, whisk the eggs, buttermilk, oil and 2 teaspoons vanilla for about 1 minute until smooth and fully blended.
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Ready when: No visible streaks of egg yolk remain.
Tip: Cold buttermilk and eggs can make the oil clump, so use room-temperature ones.
4
Make the batter
- Pour the wet mixture into the dry ingredients and whisk just until combined, about 30 seconds.
- Slowly pour in the hot coffee while whisking, then whisk 30 seconds more until smooth.
- The batter will be very thin, like heavy cream.
- Scrape the bottom of the bowl to catch any dry flour.
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Ready when: Smooth, pourable batter with no dry pockets of flour.
Tip: Don't worry about the thin batter. It's what makes the cake moist. Stop mixing as soon as it is smooth.
5
Bake the layersOven 350°F / 175°C
- Divide the batter evenly between the two pans (about 2 ¾ cups or 650 g each; weigh for even layers).
- Tap each pan gently on the counter to release large bubbles.
- Bake at 350°F (175°C) for 30 to 35 minutes, rotating the pans front to back at 20 minutes only if your oven bakes unevenly.
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Ready when: The centers spring back when lightly pressed, the edges just pull away from the pan, and a toothpick in the center comes out clean or with a few moist crumbs.
Tip: Avoid opening the oven door during the first 20 minutes, or the centers can sink.
6
Cool the layers
- Cool the cakes in their pans on a wire rack for 15 minutes.
- Run a thin knife around the edges, invert each onto the rack, peel off the parchment, and turn right side up.
- Cool completely, about 60 more minutes.
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Ready when: The cake bottoms feel neutral, not warm, to the touch.
Tip: While the cakes cool, melt the chocolate for the frosting (next step).
7
Melt the chocolate
- Place the chopped chocolate in a heatproof bowl set over a saucepan with 1 inch of barely simmering water (the bowl must not touch the water).
- Stir until smooth, about 4 minutes.
- Or microwave in 20-second bursts, stirring between each.
- Remove from the heat and let it stand 10 minutes, stirring now and then.
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Ready when: Chocolate is smooth and glossy and feels barely warm, not hot, on your fingertip.
Tip: Hot chocolate will melt the butter and make the frosting greasy and soupy.
8
Beat the butter
- In a stand mixer with the paddle, beat the 340 g softened butter on medium speed for 3 to 4 minutes until pale, creamy and noticeably fluffier.
- Scrape down the bowl and paddle halfway through.
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Ready when: The butter is pale yellow and smooth with no lumps.
9
Add sugar and cocoa
- Turn the mixer to low.
- Add the powdered sugar and cocoa in three additions, mixing each in until nearly blended before adding the next.
- Add ¼ teaspoon salt, then beat on medium for 1 minute.
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Ready when: No dry streaks remain and the mixture looks thick and dark.
Tip: Start on the lowest speed or you'll be wearing a cloud of cocoa.
10
Finish the buttercream
- Add the cooled melted chocolate, 6 tablespoons cream and 2 teaspoons vanilla.
- Mix on low to combine, then beat on medium-high for 2 minutes until fluffy and spreadable.
- If it's stiff, beat in more cream 1 tablespoon at a time; if soft, chill 10 minutes and re-beat.
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Ready when: The frosting holds a soft peak and spreads easily without tearing the cake.
Tip: Avoid overbeating at high speed, which adds air bubbles that make the frosting harder to smooth.
11
Assemble and frost
- If the layers have domed tops, trim them level with a serrated knife.
- Place one layer on a plate or turntable.
- Spread about 1 ¼ cups frosting over the top in an even layer.
- Set the second layer on top, bottom side up for a flat top.
- Spread a thin crumb coat of frosting over the top and sides, chill 10 minutes if you like, then cover with the remaining frosting, making swoops with the back of a spoon or smooth with an offset spatula.
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Ready when: The cake is fully and evenly covered with no crumbs showing through.
Tip: Tuck strips of parchment under the bottom edge to keep the plate clean, then pull them away.
12
Set and slice
- Let the cake stand at room temperature 20 minutes so the frosting sets slightly.
- Slice with a long knife dipped in hot water and wiped dry between cuts.
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Ready when: The frosting is set and not sticky on the surface when touched lightly.

Good to know

Tips

Weigh the batter into the pans for layers of equal height and even baking.
Measure flour by spooning it into the cup and leveling, or better, weigh it. Packed flour makes the cake dry.
Make sure the cake is truly cool before frosting. Even slightly warm layers will melt the buttercream and slide.
For extra-smooth frosting, beat on low for the last minute to push out air bubbles, then smooth with a warm offset spatula.

Make ahead

Bake the layers up to 2 days ahead: cool completely, wrap tightly in plastic, and keep at room temperature (or freeze up to 2 months). The buttercream can be made up to 3 days ahead and refrigerated in an airtight container; bring to room temperature and re-whip until smooth before using.

Storage & reheating

Room temperature, covered, up to 2 days (cool kitchen). Refrigerate up to 5 days in an airtight cake keeper; let slices stand 30 minutes at room temperature before serving for the best texture. Freeze unfrosted layers up to 2 months, or frosted slices wrapped tightly up to 1 month; thaw overnight in the fridge.

Substitutions

buttermilk → 1 cup (240 ml) whole milk mixed with 1 tablespoon lemon juice or white vinegar. Let it stand 5 minutes until slightly curdled, then use at room temperature.
hot brewed coffee → 1 cup (240 ml) hot water. The cake will still be chocolatey but with a slightly less deep flavor. The coffee won't taste like coffee.
neutral vegetable oil → ½ cup (113 g) melted unsalted butter, slightly cooled. Gives a more buttery flavor with a slightly firmer crumb.
heavy cream → whole milk. Use the same amount; the frosting will be slightly less rich.