Prep 1 hr
Cook 3 hrs
Taken from the Heal My Hands blog at http://healmyhands.typepad.com/heal_my_life/2007/05/darkest_chocola.html based on a Martha Stewart recipe. It's very fussy and quite a lot of work, but oh, it is impressive! Because the sugar in the French buttercream is melted into the egg yolks, it makes a smoother cream than American buttercream (which is made with confectioner's sugar). It will keep, tightly covered, in the refrigerator overnight, or up to 1 month in the freezer. Before using, let stand at room temperature until spreadable, then beat with electric mixer on high until smooth and fluffy again.
- 4 large eggs
- 2 1⁄4 cups whole milk
- 1⁄2 cup cream or 1⁄2 cup half-and-half cream or 1⁄2 cup buttermilk
- 1 cup grated bittersweet chocolate
- 1⁄4 cup cocoa powder
- 2 tablespoons sugar
- 1 1⁄4 cups pastry flour
- 2 tablespoons wheat gluten or 2 tablespoons bread flour
- 3⁄4 teaspoon salt
- 1 teaspoon baking soda
- 1 tablespoon vinegar
Rum Hazelnut French Buttercream
- 3⁄4 cup ground hazelnuts
- 4 egg yolks
- 1⁄3 cup granulated sugar
- 2 tablespoons dark rum (or liqueur of your choice)
- 1 dash salt
- 12 tablespoons unsalted butter, at room temperature
- 1⁄2 teaspoon vanilla extract
- 1 1⁄4 cups heavy cream
- 1 tablespoon light corn syrup
- 1 pinch salt
- 10 ounces semisweet dark chocolate, chopped fine
- Crepes: Mix all crepe ingredients thoroughly (a blender would not be a bad idea). Refrigerate at least 2 hours, and up to 12 before proceeding.
- Barely butter the inside of a hot 9" non-stick skillet. Pour roughly 2 tbsp of batter into the middle of the skillet and quickly swirl around to thoroughly coat the bottom of the skillet. When the edges are set, just beginning to brown, and a few bubbles are popping in the middle, about 30-40 seconds, flip the crepe over and cook the other side, just until it browns a little, 10-15 seconds. Turn the crepe out onto a plate and repeat until all the batter is gone. You should have 30 crepes.
- Buttercream: toast the hazelnut flour in a small skillet over medium-low heat, stirring frequently, until just barely golden. Watch carefully, as the tiny bits can burn very very fast. Turn out into a bowl to cool.
- In the top of a double boiler, combine egg yolks, sugar, liqueur and salt. Whisk over boiling water 4 min, or until thick and pale. Remove from heat and cool to room temperature.
- In a bowl, combine butter and vanilla. Beat with electric mixer on medium-high 5 minutes, until soft and fluffy and lighter in color. Slowly beat in the cooled egg yolks. Let stand at room temperature 20 minutes, until spreadable. Fold in the hazelnuts by hand with a spatula.
- Ganache: Bring cream, corn syrup and salt to a boil over medium heat. Remove from heat. Add chocolate and swirl pan until chocolate is covered with cream. Let stand 5 minutes, then stir until smooth.
- Assembly: spread a thin layer of butter cream on a crepe. Layer a second crepe on top. Continue spreading cream on crepes until all the crepes are used up. Refrigerate 15 minutes until firm.
- Place crepe stack on a wire rack set over a rimmed baking sheet. Pour 1/2 cup of ganache over the top of the cake and spread to edges. Use remaining ganache to cover the sides of the cake. Sprinkle top with toasted chopped hazelnuts and refrigerate until set, about 20 minutes. Cake will keep in refrigerator about 3 days (if it lasts that long).