Serves: Makes 2 (9-inch) cake layers, serving 8 to 12
- ½ cup (2½ ounces) unsifted unsweetened Dutch-process cocoa powder. Be sure to use unsweetened Dutch-process cocoa powder; natural cocoa powder will react unfavorably with the baking powder
- ½ cup (4 ounces) plus 1 cup (8 ounces) water
- 1½ sticks (6 ounces) unsalted butter, softened (65° to 68°F)
- 1 cup (7 ounces) granulated sugar
- ¾ cup (6 ounces) firmly packed light brown sugar
- 3 large eggs, at room temperature
- 2 teaspoons pure vanilla extract
- 2 cups (7 ounces) sifted cake flour
- ¼ cup (1¼ ounces) unbleached all-purpose flour
- 2 teaspoons baking powder
- ¼ teaspoon salt
- 1 recipe Dark Chocolate Ganache, prepared at least 8 hours ahead, covered, and stored at room temperature
Dark Chocolate Ganache
- 12 ounces semisweet or bittersweet chocolate (up to 60 percent cacao), finely chopped
- 1½ cups heavy whipping cream
Preheat the oven to 350°F and position oven racks in the lower and upper thirds. Lightly coat the pans with butter, oil, or high-heat canola-oil spray and line the bottoms with rounds of parchment paper.
Mix the cocoa powder: Place the cocoa powder in a small bowl. Heat ½ cup of the water in the small saucepan just until it begins to simmer. Pour it over the cocoa and whisk or stir until blended and smooth. Add the remaining 1 cup water and stir until the mixture is smooth. Set aside until the mixture cools to room temperature. If it is warm, it will melt the butter and ruin the texture of your cake.
Cream the butter with the sugars: Place the butter, granulated sugar, and brown sugar in the bowl of the stand mixer. Beat on medium-high speed until very light in color, 4 to 5 minutes. You can also use a hand mixer and a medium bowl, although you may need to beat the mixture a little longer to achieve the same results. Scrape down the bowl with the spatula.
Add the eggs: Beat the eggs and vanilla in the other small bowl to blend. With the mixer on medium, add the eggs to the butter mixture about 1 tablespoon at a time, allowing each addition to completely blend in before adding the next. About halfway through, turn off the mixer and scrape down the bowl, then resume adding the eggs. Scrape down the bowl again.
Add the dry and wet ingredients alternately: With the fine-mesh strainer, sift the cake flour, all-purpose flour, baking powder, and salt into the medium bowl and blend with the cleaned whisk. With the mixer on the lowest speed, add the flour mixture and the cocoa water alternately, beginning with one-third of the flour mixture and half the cocoa water. Repeat, then finish with flour mixture. Scrape down the bowl and finish blending the batter by hand, if necessary.
Bake the cake: Divide the batter evenly between the two prepared pans and smooth the tops. Bake for about 30 minutes, or until the tops are firm to the touch and a toothpick inserted into the centers comes out clean. Transfer to a rack to cool completely.
Unmold the cakes: Run the thin and flexible knife or spatula around the edge of a pan to loosen the cake. Place a cake cardboard on top of the pan, hold the two together, and flip over. Remove the pan, leaving the parchment on the cake. Set the second cake cardboard or plate on top, then flip again. The cake will now be right side up. Repeat with the remaining cake.
Level the cakes. Turn one over onto a cake cardboard or serving plate, and remove the parchment paper. Spread a generous ¾ cup sabayon cream over the surface. Turn the second cake over onto the cream, cut side down. Peel off the parchment paper. Voila!-a crumb-free surface for frosting. Use the remaining frosting to cover the top and sides of the cake. Serve immediately or refrigerate until needed.
Storing: The unfrosted cakes can be wrapped in plastic and held at room temperature for 1 day. They can also be frozen, double-wrapped in plastic, each one inside a resealable plastic freezer bag, for up to 4 weeks. Leave the parchment paper intact. To thaw, unwrap the cakes and defrost at room temperature for about 1 hour. Once frosted, refrigerate for up to 3 days under a cake dome. If it has been cut, simply press a piece of plastic wrap firmly against the cut surfaces to keep it fresh.
Dark Chocolate Ganache
Place the chocolate in the medium bowl. Heat the cream in the small saucepan over medium heat until it begins to boil. Immediately pour the cream over the chocolate. Let the mixture sit for 1 minute, then gently whisk until the ganache is completely smooth and blended. If you are using a high-percentage chocolate and the mixture looks broken or curdled at this point, stir in an extra tablespoon or two of cream, just until the mixture smooths out again. Use as directed.
Let the ganache cool for 1 hour, then cover with plastic wrap and set aside to finish cooling at room temperature until it has the consistency of frosting, 8 to 10 hours. If you make it the night before, it will be the perfect texture for frosting cakes and cupcakes in the morning.
Storing The ganache may be prepared up to 2 days ahead and kept at room temperature.