(Makes one 9-inch round cake, 12 to 14 servings)
1 tablespoon unsalted butter, melted, for the cake pans
1 tablespoon all purpose flour, for the cake pans
2 cups cake flour, sifted
1 teaspoon baking soda
1/4 teaspoon salt
1/2 cup unsweetened natural cocoa powder, sifted
1/2 cup hot water
1 cup buttermilk
1 1/2 teaspoons Rain’s Choice pure Vanilla Extract
4 ounces (1 stick) unsalted butter, softened
1–1/2 cups firmly packed golden brown sugar
1/2 cup granulated Rain’s Choice Vanilla Sugar
2 large eggs at room temperature
(makes 4 cups)
2 large eggs at room temperature
2 large egg yolks at room temperature
1 cup plus 2 tablespoons Rain’s Choice Vanilla Sugar
1/2 cup water
1/4 teaspoon (heaping) cream of tartar
14 ounces (3 1/2 sticks) unsalted butter, softened
3 to 4 tablespoons pure Rain’s Choice pure Vanilla Extract
Center a rack in the oven and preheat to 350 degrees F. Brush the insides of two 9 by 2 inch cake pans with melted butter, then dust with flour and shake out the excess. Cut two rounds of parchment paper to fit the bottoms of the cake pans and place in the pans. Brush the parchment rounds with butter.
Sift together the flour, baking soda, and salt.
Place the cocoa powder in a mixing bowl and add the hot water. Stir together until the cocoa is dissolved and there are no lumps. Combine the buttermilk and vanilla in a measuring cup.
Place the butter in the bowl of a stand mixer or in a mixing bowl. Use the flat beater attachment or a hand-held mixer to beat the butter until it is light and fluffy, about 2 minutes. Add the sugars and beat until the mixture is light and fluffy, about 8 minutes. Stop occasionally and scrape down the sides of the bowl with a rubber spatula.
Beat the eggs lightly with a fork to blend them, then add slowly to the butter/sugar mixture. Continue beating until smooth and well blended, stopping as needed to scrape down the sides of the bowl. Alternately add the dry ingredients and buttermilk in 4 stages. Blend thoroughly after each addition.
Divide the batter between the prepared pans. Use the rubber spatula to smooth and even the tops. Bake the cakes for 30 to 35 minutes, until a toothpick inserted in the center comes out clean.
Remove the cakes from the oven and cool on racks for 15 minutes. Place a 9-inch cardboard cake circle over the mouth of the cake pans and invert. Peel off the parchment paper from the back of the cakes. Place another cardboard cake circle over the back of the cakes and invert again, so the top is facing up. Leave to cool completely. Fill and frost immediately or cover the cakes with plastic wrap and hold at room temperature for no longer than 2 days. The cakes can be frozen to keep longer.
Combine the eggs and yolks in the bowl of an electric stand mixer or in a mixing bowl. Use the wire whip attachment or a hand-held mixer and beat on medium-high speed until very pale colored and the mixture holds a slowly dissolving ribbon when the beater is lifted, about 5 to 8 minutes.
At the same time, combine the sugar, water, and cream of tartar in a 2-quart heavy-duty saucepan and bring them to a boil over high heat. Cook the mixture until it reaches 242 F on a candy thermometer. Wash down the inside of the pan with a pastry brush dipped in warm water 2 or 3 times as the mixture is cooking, to prevent crystals from forming.
When the sugar is at the correct temperature, turn the mixer speed to low and pour the sugar syrup into the eggs in a slow, steady stream. Then turn the mixer speed up to medium-high and beat until the bowl is cool to the touch, 5 to 8 minutes. Beat in the softened butter 2 tablespoons at a time and continue to beat the buttercream until it becomes fluffy and homogenous, 2 to 3 minutes.
Stop the mixer and add the vanilla extract. Beat the buttercream, stopping to scrape down the sides of the bowl with a rubber spatula, until it is thoroughly blended.
This buttercream can be prepared in advance of use and kept refrigerated, covered, for 3 days, or frozen for up to 4 months. If frozen, defrost in the refrigerator for 24 hours before using. To rebeat the buttercream, place chunks of it in the bowl of a mixer and place the bowl in a saucepan of warm water. When the buttercream begins to melt around the bottom and sides of the bowl, remove the bowl from the water, wipe it dry, and beat the buttercream with the flat beater of a stand mixer or with a hand-held mixer on medium speed until it is fluffy, 2 to 3 minutes. To assemble the cake cut each layer in half horizontally. Place one bottom layer on a cake decorating turntable or a countertop. Reserve 1/3 cup of the buttercream for the final decoration. Spread some of the buttercream evenly over the cake layer. Position another layer of cake on top of the buttercream and spread more buttercream over this layer, evenly and smoothly. Repeat with the remaining two cake layers. Spread the remaining buttercream over the sides and top of the cake. Use the flexible blade spatula to smooth and even the top.
Sprinkle the nuts onto a sheet of waxed paper. Use the flexible blade spatula to carefully lift the cake from the bottom and wedge your hand under it, lifting it up. With your other hand press the nuts into the sides of the cake up to the top. Excess nuts will fall back onto the waxed paper. Fit a 12-inch pastry bad with a #5 large star tip and fill with the reserved buttercream. Pipe a row of shells around the top outside edge of the cake.
Carefully place the cake onto a serving plate and sprinkle any remaining nuts over the top. Serve the cake immediately or cover carefully and refrigerate until 30 minutes before serving.