By Chef Donald Wressell | Photography by Antonis AchilleosMakes 1 (8-inch) round double-layer cake, serving 8–12For the cake: 1¾ cups plus 1 tablespoon all-purpose flour1½ cups plus 4 tablespoons sugar1¼ teaspoons salt1 tablespoon baking soda⅞ cup water⅓ cup plus 2 tablespoons Guittard Cocoa Rouge⅞ cup Buttermilk½ cup plus 2 tablespoons vegetable oil2 whole large eggs1 teaspoon vanilla extractFor the 64% ganache: 2 (6-ounce) packages or 6 (2-ounce) bars Collection Etienne Chocolate Baking Bars Semisweet 64%, chopped1¼ cup 35% cream or heavy whipping cream2 tablespoons invert sugar or light corn syrup3 ounces or 6 tablespoons unsalted butter, softenedFor the white chocolate buttercream: ½ cup pasteurized egg whites½ cup plus 2 tablespoons sugarPinch of salt¼ teaspoon vanilla extract12 ounces or 3 sticks unsalted butter, softened¾ cup (before melting) Collection Etienne 31% White Chocolate wafersTo make the cake:Bring water to a boil, turn off heat and add cocoa powder, stir well, then set aside to cool. Put the dry ingredients in a stand mixer with a paddle attachment. Mix until well incorporated, about 1 minute. Add buttermilk, oil, eggs and vanilla all at once to the dry while mixing until all dry ingredients are hydrated. Scrape well. Then mix for 2 minutes. Scrape well. Add the cocoa/water mixture. Scrape. Mix to combine about 30 seconds. Preheat oven to 350°F. Divide batter into 2 (8-inch) round buttered and papered cake pans. Let the cake batter rest for 30 minutes before baking. Place the cake pans in the middle rack of the oven. Bake for 30–35 minutes. Allow cakes to cool to room temperature, then refrigerate until completely cold. About 1 hour. To make the ganache: Boil cream with the corn syrup Pour cream into a bowl with the chopped chocolate. Let stand for 3 minutes. Stir with a rubber spatula to create an emulsion. Add the butter and stir. Pour chocolate into a shallow flat glass baking dish. Allow ganache to set at room temperature for 1 hour or until it is spreadable. Ganache can be made the day before. Cover the ganache if this is done.To make the buttercream: Create a Swiss meringue by placing the sugar, salt and egg whites in large metal mixer bowl set over simmering water. Whisk constantly until the sugar dissolves and the mixture is very thin and warm, about 115°F. Remove the bowl from the heat and whisk on high speed in a stand mixer until stiff peaks form, about 5 minutes. Continue beating on low speed until cool, about 10 minutes. Add small pieces of the cool, softened butter on low speed. Gradually whisk in the melted and cooled white chocolate. Continue to whip on medium until buttercream is smooth and shiny.To assemble: Using a serrated knife, level the tops of both cakes. Cut both cakes in half horizontally, creating 2 a total of 4 layers. Place 1 layer of cake on a cardboard circle. Put ⅓ of the ganache on the cake and spread uniformly to coat. Carefully place second cake layer on the ganache and repeat until you have 4 layers of cake sandwiched with 3 layers of ganache. Chill cake for 30 minutes. Apply a “crumb coat” of white chocolate buttercream to the assembled cake. Chill for 15 minutes. Apply a finish coat of white chocolate buttercream.Chef Wressell’s tips: 1) Letting the cake batter rest for 30 minutes before baking allows the leavening to settle and prevents the fast rise and then sinking of the center of the cake.2) Line a baking sheet with parchment and sprinkle with granulated sugar before inverting the cooled cake layers and placing in the refrigerator. The sugar prevents the cake from sticking to the parchment.