Chocolate-Orange Bûche de Noël

Preparation

1. Make cake:

   Step 1

   Preheat oven to 350°F. Butter 15 x 10 x 1-inch jelly-roll pan. Line bottom with waxed paper, allowing 1-inch overhang on short sides. Butter paper. Lightly dust paper and pan with flour; tap out excess. Using electric mixer, beat egg whites in large bowl until foamy. Add cream of tartar and beat until soft peaks form. Gradually add 6 tablespoons sugar, beating until stiff peaks form. Set aside.

   Step 2

   Beat egg yolks, 1/3 cup cocoa powder and remaining 6 tablespoons sugar in another large bowl until thick, about 2 minutes. Stir 1/4 of whites into yolk mixture to lighten. Fold in remaining whites. Gently spread batter in prepared pan.

   Step 3

   Bake until cake springs back when pressed in center, about 15 minutes. Transfer pan to rack. Cool completely. Sift remaining 1 tablespoon cocoa powder over cake. Line baking sheet with foil. Invert cake onto sheet. Peel off paper.

2. Make filling:

   Step 4

   Place 2 tablespoons boiling water in small bowl. Sprinkle gelatin over. Let soften 10 minutes. Heat 1/4 cup cream in small saucepan over medium-low heat just until warm. Add to gelatin mixture; stir until gelatin dissolves. Using electric mixer, beat remaining 1 1/4 cups chilled cream, powdered sugar, orange peel and vanilla in large bowl until soft peaks form. Add gelatin mixture. Beat until stiff peaks form.

3. Step 5

   Spread filling over cake, leaving 1-inch border on sides. Using foil as aid and starting at 1 long side of cake, gently roll up cake, enclosing filling. Arrange roll, seam side down, on platter. Cover tightly and refrigerate until filling is set, at least 8 hours or overnight.

4. Make ganache:

   Step 6

   Bring cream to simmer in heavy medium saucepan. Remove from heat. Add chocolate, corn syrup and liqueur. Stir until mixture is smooth. Let ganache stand until cool and thick.

   Step 7

   Whisk ganache just until soft peaks form (do not overmix). Spread ganache over roll. Using tines of fork, draw lines through ganache to represent tree bark. (Roll can be made 1 day ahead. Tent with foil and refrigerate.)

5. Step 8

   Sift powdered sugar over roll. Surround with chocolate truffles.