Bûche de Noel (Yule Log)
This traditional French dessert is shaped and iced to resemble a log, but inside it is a tender sponge cake moistened with rum syrup and rolled up with buttercream. Chef Bonnot includes miniature meringue mushrooms as garnish; they can be made a day ahead.
- Genoise (Sponge Cake)
- Eggs - 8, separated
- Sugar - 1 cup plus 2 heaping tablespoons
- Pinch of salt
- Lemon Zest - 1 teaspoon, grated
- All-Purpose Flour - 9 ounces, sifted
- Sugar - 2 cups
- Water - 1 cup
- Few drops lemon juice
- Egg Yolks - 8
- Unsalted Butter - 1 pound, chilled
- Unsweetened Cocoa - 3 tablespoons
- Dark Rum - 1 tablespoon
- Red and green food coloring
- Warm Water - 1/4 cup
- Sugar - 1/2 cup
- Lemon Juice - 1/2 teaspoon
- Dark Rum - 1/4 cup
- Meringue Mushrooms
- Egg Whites - 2
- Vanilla - 1/2 teaspoon
- Sugar - 1/2 cup
- Cocoa for dusting
To make the genoise: Butter and flour an 11-by-17-by-1-inch jelly roll pan. Line the bottom with buttered parchment paper. Preheat the oven to 375 F. In a large bowl, combine the egg yolks with 3/4 cup plus 2 tablespoons of the sugar. Whisk until pale yellow and thick enough to form a ribbon. Fold in the lemon zest.
In a separate mixing bowl, whip the egg whites and salt until soft peaks form. Add the remaining sugar and continue to beat until stiff but not dry. Gently fold the beaten whites, one-half at a time, into the egg yolk mixture. Sprinkle one third of the flour, over the batter and fold in gently. Repeat in two more additions until all the flour has been incorporated.
Turn the batter into the prepared pan and bake for 12 minutes, until lightly browned; do not overbake or the cake will crack when rolled. Remove from oven and allow to cool in the pan; invert onto a cake rack and remove the parchment paper. If prepared in advance, cover the pan with plastic wrap and refrigerate until assembly, then remove from pan.
To make the buttercream: Combine the sugar, water, and lemon juice in a saucepan. Boil, uncovered, until the sugar reaches the soft-ball stage (236 – 238 F on a candy thermometer). Place the egg yolks in a large mixing bowl. Using an electric mixer on high speed, incorporate the sugar mixture into the yolks in a slow, steady stream. Continue to beat until the yolk and sugar mixture is completely cool.
Add the butter, about 2 tablespoons at a time, to the egg mixture. Beat until smooth, then refrigerate 10 to 15 minutes. Reserve about 1 cup of buttercream for decoration. Flavor the remaining buttercream with cocoa and rum. Whisk until smooth. Divide the cup of reserved buttercream into three small bowls. Tint one portion with red food coloring; color another third green, and keep the remaining third white.
To make the syrup: Combine all ingredients in a small bowl and stir until the sugar is dissolved.
To assemble: Place the genoise on a large sheet of parchment paper. Moisten the cake with the syrup (do not soak). Spread a thin layer of buttercream onto the cake. Roll the cake lengthwise, using the parchment paper to guide it as you roll.
Trim 1 to 2 inches from each end of the roll, cutting at an angle. Place the roll, seam-side down, on a serving tray. “Glue” the trimmed pieces onto the log with buttercream to resemble cut branches. Brush the log with the syrup.
Ice the ends of the log and limbs with white buttercream. Spread the rest of the log with chocolate buttercream, then use the tines of a fork or a thin artist’s spatula to texture the icing to look like tree bark.
With a small pastry bag, decorate the log with vines and leaves in green buttercream. Pipe berries onto the vines with the red buttercream. Gently pat a small spot of cocoa in the center of both ends and limbs to simulate knotholes. Refrigerate until service. At the last minute, garnish the presentation with the meringue mushrooms.
Preheat the oven to 175 F. Line a baking sheet with parchment paper. With an electric mixer, beat the egg whites until foamy. Add the vanilla. With the mixer running, gradually add the sugar. Beat until the mixture turns glossy and forms stiff peaks.
Using a pastry bag fitted with a large plain tip, pipe individual meringues the size and shape of mushroom caps and mushroom stems onto the prepared baking sheet. Make enough pieces for 10 mushrooms. The rest of the meringue can be piped into individual kisses for other use. Bake 3 to 4 hours, until crisp and dry. Remove from oven, cool, and store tightly covered until use.
To assemble: Lightly dust the meringue mushroom pieces with cocoa. Using the point of a small knife, hollow out a small attachment point for a stem in the underside of each mushroom cap. Glue the mushroom stems into the caps using a little of the buttercream in the above recipe.