This impressive and sumptuous special-occasion dessert, composed of two “go-to” recipes from Dominique Ansel’s book “Everyone Can Bake,” is easier to make than you might think. Christopher Kimball’s Milk Street Television did modify both his chocolate cake and the mascarpone whipped ganache, and also added a coffee syrup for moistening the cake before assembly when preparing this recipe in Season Five.
A chocolate-hazelnut spread (such as Nutella) is folded into half of the whipped ganache to sandwich between the cake layers; the remaining whipped ganache is spread on top, creating a unique striped effect. The cake itself has the deepest, richest flavor and color when made with a good-quality dark Dutch-processed cocoa powder. Valrhona yielded the best results.
Part of the beauty of this dessert is that the cake and filling can be made ahead; even after assembly, the dessert will hold nicely for up to 24 hours. Make the ganache base and the cake a day in advance and refrigerating them separately. The following day, whip the ganache, assemble the dessert and refrigerate for at least two hours or for up to an entire day. For neat slices, cut the cake with a serrated knife that’s been warmed in hot water and wiped dry.
To store leftovers, press plastic wrap directly against the cakes’ cut sides and refrigerate for up to two days. Don’t whip the ganache before the mixture is completely cold and set. If whipped too soon, it won’t attain the proper light, fluffy volume. When spreading the whipped ganache on the top layer of cake, the less you manipulate it, the better. Overworking may cause the ganache to become grainy and lose its velvety smoothness. Finally, don’t allow the cake to stand for more than about 30 minutes before serving; if it loses too much of its chill, the filling softens and the layers may begin to slide apart.
Serves 12
INGREDIENTS
FOR THE WHIPPED GANACHE:
170 grams (6 ounces) white chocolate, finely chopped
1 packet (7 grams) unflavored gelatin
2 cups heavy cream
8-ounce container mascarpone cheese
2 tablespoons honey
FOR THE CAKE:
40 grams (1⁄2 cup) unsweetened Dutch-processed cocoa powder, plus more for the pan
216 grams (1 2⁄3 cups) all-purpose flour
321 grams (1 1⁄2 cups) white sugar
1⁄2 teaspoon baking powder
1⁄2 teaspoon baking soda
1⁄4 teaspoon table salt
2 large eggs
1 cup buttermilk, preferably low-fat
2⁄3 cup grapeseed or other neutral oil
2 teaspoons vanilla extract
FOR THE SOAKING SYRUP/ASSEMBLY:
71 grams (1⁄3 cup) white sugar
1 teaspoon instant espresso powder
95 grams (1⁄3 cup) chocolate-hazelnut spread, such as Nutella
35 grams (1⁄4 cup) toasted skinned hazelnuts, half roughly chopped, half very finely chopped, reserved separately
INSTRUCTIONS
WHIPPED GANACHE
STEP ONE. Put the white chocolate in a medium bowl; set aside.
STEP TWO. In a small bowl, stir together the gelatin and 2 tablespoons water; set aside.
STEP THREE. In a medium saucepan over medium, combine the cream, mascarpone, and honey. Cook, stirring often, until the mascarpone is fully melted and the mixture begins to bubble at the edges, 6 to 8 minutes. Remove from the heat, add the gelatin mixture and whisk until completely dissolved.
STEP FOUR. Immediately pour the cream mixture over the white chocolate, then let stand for about 1 minute. Whisk the chocolate mixture until completely smooth. Press plastic wrap directly against the surface and cool to room temperature, then refrigerate until well chilled and fully set, at least 4 hours or up to 24 hours.
CAKE
STEP FIVE. Heat the oven to 350°F with a rack in the middle position. Mist the bottom and sides of a 9-by-2-inch round cake pan with cooking spray, line the bottom with a round of kitchen parchment, then mist the parchment. Using a paper towel, evenly spread the oil. Dust the pan evenly with cocoa and knock out any excess.
STEP SIX. In a large bowl, whisk together the cocoa, flour, sugar, baking powder, baking soda, and salt.
STEP SEVEN. In a medium bowl, whisk the eggs, buttermilk, oil, and vanilla until homogeneous. Add the liquid ingredients to the dry ingredients, and, using a large silicone spatula, fold until the batter is completely smooth.
STEP EIGHT. Pour the batter into the prepared pan, then rap the pan 4 or 5 times against the counter to release any large air bubbles. Bake until a toothpick inserted at the center of the cake comes out clean, about 45 minutes. Cool in the pan on a wire rack for about 20 minutes. Run a paring knife around the edge of the cake to loosen, then invert it onto the rack and lift off the pan. Remove and discard the parchment, then carefully re-invert the cake and let cool completely. Wrap the cake in plastic wrap and set on a large, flat plate. Refrigerate for at least 4 hours or up to 24 hours.
SOAKING SYRUP/ASSEMBLY
STEP NINE. When ready to assemble, make the soaking syrup. In a 1-cup liquid measuring cup or small microwave-safe bowl, stir together the sugar and 1⁄4 cup water. Microwave on high for 30 seconds, then stir until the sugar is fully melted and the syrup is clear. Add the instant espresso and whisk until dissolved. Cool to room temperature.
STEP TEN. Unwrap the chilled cake and set it on a cutting board or other flat surface. Using a pastry brush, brush the sides of the cake evenly with 1 1⁄2 tablespoons of the syrup. Using a serrated knife and a gentle sawing motion, carefully slice off and remove the domed surface of the cake, creating a level top. Now slice the cake horizontally into 2 even layers. Carefully lift off the top layer and set aside; transfer the bottom layer to a cake platter. Brush the surface of both cake layers with all of the remaining syrup, dividing it evenly; the layers should be well moistened but not soggy.
STEP ELEVEN. Transfer the chilled ganache to the bowl of a stand mixer. Using the whisk attachment, whip on high until lightened and fluffy, about 5 minutes, scraping the bowl once.
STEP TWELVE. Meanwhile, put the chocolate-hazelnut spread in a large bowl and stir to smooth and soften. Scoop half (about 440 grams/3 cups) of the whipped ganache into the bowl containing the chocolate-hazelnut spread, and, using a silicone spatula, gently fold until homogeneous.
STEP THIRTEEN. Scoop the chocolate-hazelnut ganache onto the center of the bottom cake layer, then use an offset icing spatula to spread it in an even layer, all the way to the edges of the cake.
STEP FOURTEEN. Using a wide metal spatula, lift the top cake layer and gently center it on the chocolate-hazelnut ganache layer; do not press on the cake.
STEP FIFTEEN. Using the whisk attachment, re-whip the remaining ganache on high until smooth, about 30 seconds. Scoop it onto the center of the top layer of the cake and spread it in an even layer or, if desired, create swirls in the surface. Scatter the finely chopped nuts over the top, followed by the roughly chopped nuts. Refrigerate uncovered for at least 2 hours or for up to 24 hours. Before serving, let the cake stand at room temperature.
