Black Forest Cake

To make the cake:

1. Preheat the oven to 325°F (165°C or gas mark 3). Grease and lightly flour the pan or pans of your choice, or coat lightly with nonstick spray and line with parchment paper.
2. Melt the butter over low heat, and set it aside to cool to room temperature. Whisk together the whole wheat pastry flour, cocoa and all-purpose flour in a medium bowl; set aside.
3. Combine the eggs, egg yolks, salt, vanilla and sugar in a large bowl. Place the mixing bowl over a larger bowl half filled with hot tap water. Whisk the mixture until it feels just slightly warm to the touch when you test it in the center with your finger (3 to 5 minutes). If you want to be precise, use a thermometer—the egg mixture should be at 100°F (38°C) and no warmer. Warming the eggs and dissolving the sugar this way will ensure they reach the highest possible volume when beaten.
4. Place the mixing bowl on your stand mixer and beat with a wire whip until the mixture is tripled in volume and a very pale yellow color. This will take 5 to 8 minutes on high speed, depending on the power of your mixer. When it’s done, the egg mixture should fall off the whisk and mound for a moment before disappearing back into the bowl.
5. Remove the bowl from the mixer and use a whisk to gently fold in the reserved flour-cocoa mixture by hand, until no streaks of flour remain. Gently fold in the melted, cooled butter, a little at a time, taking care not to mix more than necessary to get the butter to disappear. If you pour too much in at once, the butter will collapse the egg foam, then pool on the bottom of the mixing bowl, making it harder to distribute. The volume of the batter will decrease a bit during this process, but a light touch and quick, confident strokes from the bottom of the bowl up through the batter will see you through.
6. Pour the batter into the prepared pan(s). Bake until the chocolate is fragrant, and the top springs back when lightly touched in the center, 25 to 27 minutes for layers, 21 to 23 minutes for sheet cake.
7. Remove the cake from the oven and place on a rack to cool completely before assembling the cake. While the cake is cooling, make the simple syrup and whipped cream.

To make the syrup:

1. Bring the water and sugar to a simmer in a small saucepan over medium heat, stirring until the sugar dissolves. Remove from the heat and stir in the Kirschwasser (or flavoring). Set aside to cool to room temperature. Reserve the cherry pie filling for assembling.

To make the whipped cream:

1. Place the water in a small heatproof bowl. Sprinkle the gelatin over the water, and let it sit for 5 minutes to absorb the water. Melt the gelatin over simmering water or at low power in the microwave for a very short time (10 to 15 seconds). Let the gelatin cool to room temperature.
2. Whip the heavy cream with the vanilla in a large mixing bowl until it begins to thicken and the whisk begins to leave tracks as it moves through the cream.
3. With the mixer running on medium speed, pour in the melted gelatin. Once the gelatin is incorporated, stop the mixer and add the confectioners’ sugar. Resume beating the cream until it forms medium peaks.

To assemble  and frost the cake:

1. If you’ve baked a sheet cake, cut the cooled cake into six 4 x 8-inch (10x20 cm) strips or six 6-inch (15cm) rounds, as desired. If you’re using 8- or 9-inch (20-22cm) layers, remove them from their pans.
2. Brush the tops of the layers with simple syrup. Each layer will need ½ cup (120 ml) of syrup, ¼ cup (60 ml) each for top and bottom. Choose one layer to be the bottom of the cake, and place it, soaked-side down, on a serving plate whose edges are covered with wax paper or parchment paper to keep it clean. Soak the other side of the layer with another ¼ cup (60 ml) of syrup, and place it in the freezer for 30 to 45 minutes.
3. After the layer has firmed up in the freezer, spread ⅔ cup (about 240g) pie filling over it. Place the next layer, soaked side down, on top of the filling. Brush the top of this layer with syrup, and return the cake to the freezer once more for 30 to 45 minutes, until firm to the touch.
4. If your cake is to have 3 layers, use another ⅔ cup (240g) of filling on the top, place the last layer over the filling, soaked side down, and brush the top with another ¼ cup (60 ml) of syrup. If you’re building a 2-layer cake, place the second layer on top of the filling, soaked side down, brush the top with simple syrup, and freeze the cake for another 30 minutes.
5.  Cover the top and sides with Stabilized Whipped Cream. Pipe rosettes of whipped cream around the top edge of the cake. Place a cherry on top of each rosette, and fill the area in between with chocolate shavings.

Instead of an 8-inch 3-layer cake, this recipe can also make a 9-inch (22.5 cm) 2-layer cake; two 6-inch (15 cm) round 3-layer cakes or two 4 x 8-inch (10x20 cm) rectangular layer cakes, 8 servings each.