Chocolate Layer Cake with Ganache

Before you start

This cake is built for maximum chocolate flavor and moisture. Cocoa powder bloomed in hot coffee releases more of its flavor, and oil instead of butter keeps the crumb soft and tender even when the cake is cold. The batter is thin, almost like heavy cream, which surprises first-time bakers but is exactly right; it bakes into tender, springy layers.

The frosting is a simple ganache of equal weights chocolate and cream, left to thicken at room temperature until it reaches a peanut-butter consistency. That wait is the main timing decision: too fluid and it runs off the cake, too firm and it tears the crumb. Use a chocolate you like eating, since ganache tastes exactly like it.

Ingredients

• Cake250 g (2 cups, spooned and leveled) all-purpose flour
• 400 g (2 cups) granulated sugar
• 75 g (¾ cup + 2 tbsp) unsweetened cocoa powder — natural or Dutch-process
• 2 tsp baking soda
• 1 tsp baking powder
• 1 tsp fine salt
• 2 large eggs — room temperature
• 240 ml (1 cup) buttermilk — room temperature
• 120 ml (½ cup) neutral oil
• 2 tsp vanilla extract
• 240 ml (1 cup) hot brewed coffee — or hot water
• Ganache340 g (12 oz) semisweet or bittersweet chocolate (55–65%) — finely chopped
• 340 g (1½ cups) heavy cream
• 30 g (2 tbsp) unsalted butter — softened
• Pinch fine salt

Method

1. Heat the oven to 180°C (350°F). Grease the pans, line the bottoms with parchment and dust the sides with cocoa.
2. Make the ganache first so it can thicken: heat the cream until it just simmers at the edges, pour it over the chopped chocolate and leave for 3 minutes. Stir from the center outward until smooth and glossy, then stir in the butter and salt. Leave at room temperature, stirring every 30 minutes.
3. Whisk the flour, sugar, cocoa, baking soda, baking powder and salt in a large bowl, breaking up cocoa lumps.
4. Add the eggs, buttermilk, oil and vanilla and whisk for about 1 minute, until thick and smooth. Slowly whisk in the hot coffee. The batter will be thin and pourable.
5. Divide the batter between the pans. Bake for 30 to 35 minutes, until the tops spring back and a toothpick in the center comes out clean or with a few moist crumbs.
6. Cool in the pans for 15 minutes, then turn out onto racks and cool completely, about 1½ hours. The layers are tender, so handle them with the flat of your hand underneath.
7. When the ganache holds soft peaks and has the consistency of smooth peanut butter, set one layer on a plate and spread about a third of the ganache over it. Add the second layer upside down and cover the top and sides with the rest, swirling with the back of a spoon.

Tips for success

• To speed up the ganache, refrigerate it, stirring every 10 minutes, but watch closely; it goes from fluid to firm quickly at the edges.
• For a lighter, fluffier frosting, whip the thickened ganache with a hand mixer for 30 to 60 seconds until it lightens in color. Stop early, as overwhipping makes it grainy.
• Freezing the cooled layers for 30 minutes makes this soft cake much easier to stack.

Substitutions

Hot coffee

Hot water works; the chocolate flavor is a little less deep. Decaf coffee keeps the depth without much caffeine.

Buttermilk

Use 240 ml milk with 1 tbsp vinegar, rested 5 minutes. The crumb is just as moist.

Ganache frosting

A chocolate buttercream is sweeter and pipes more crisply, but lacks the dense, truffle-like quality of ganache.

Variations

Sheet cake

Bake in a 23 x 33 cm (9 x 13 in) pan for 35 to 40 minutes and use half the ganache poured over the top.

Troubleshooting

Ganache split and looks oily

The cream was too hot or it was stirred too hard while warm. Whisk in 1 to 2 tbsp warm milk, a little at a time, until it comes back together.

Layers sank in the center

Underbaked or too much leavening from heaped spoons. Level your measures and bake until the center springs back.

Cake tastes bitter

Strong dark-roast coffee or a very bitter natural cocoa. Use a medium roast or water, or switch to Dutch-process cocoa.

Storage

Keep the cake under a dome at cool room temperature for up to 2 days, or refrigerate for up to 5 days. Chilled ganache firms up, so let slices sit out for 30 minutes before serving.

Safety notes

Coffee in the batter adds a small amount of caffeine per slice; use decaf if that matters to you. Do not eat the raw batter. Contains wheat, egg and milk.