Cakes resembling Yule logs are very popular at Christmastime in Canada and the United States. Though you’ll see them in bakery windows elaborately decorated with marzipan woodland animals and meringue mushrooms, we went with a simpler but more elegant look. 

Directions
Put oven rack in middle position and preheat oven to 350*F. Butter a 15- by 10- by 1-inch baking pan and line bottom with wax paper or parchment. Butter paper and dust with flour, knocking out excess. 

Pulse walnuts, flour, salt, cinnamon, and 2 tablespoons sugar in a food processor until nuts are finely chopped.
Beat together yolks, whiskey, vanilla, and 1/3 cup sugar in a large bowl with an electric mixer at high speed until thick and pale and forms a ribbon that takes 2 seconds to dissolve when beaters are lifted, 5 to 8 minutes in a standing mixer or 8 to 12 minutes with a handheld. Fold in nut mixture in 4 batches. 

Beat whites with a pinch of salt in another bowl with cleaned beaters at medium speed until they just hold soft peaks. Add remaining 2 tablespoons sugar 1/2 tablespoon at a time, beating, and continue to beat until whites just hold stiff peaks. 

Fold one fourth of whites into yolk mixture to lighten, then fold in remaining whites gently but thoroughly. Stir 1/2 cup batter into butter in a small bowl until combined, then fold butter mixture into batter gently but thoroughly. Spread batter evenly in baking pan and rap once on counter to help eliminate air bubbles.
 
Bake cake until firm to the touch, pale golden, and beginning to pull away from sides of pan, 12 to 16 minutes. Cool cake in pan on a rack 15 minutes, then loosen sides with a knife. Put a sheet of foil over cake and invert rack over foil, then flip cake onto rack and remove wax paper. Cool completely. 

Slide cake (on foil) off rack. Spread 1 1/4 cups buttercream evenly over cake and sprinkle with chopped brittle. Using foil as an aid, roll up cake, jelly-roll style, beginning with a short end. Carefully transfer cake with a long metal spatula to a platter and remove foil. 

Frost cake with about 1 1/2 cups buttercream, then chill cake until frosting is firm, about 30 minutes. (If you plan to finish assembling cake within 1 hour, keep remaining 1/4 cup buttercream at room temperature. If not, chill remaining buttercream, covered.) 

Cut a thin slice from one end of log (to make end even), then, starting about a 1/2 inch in from cut edge, cut a diagonal piece from same end of cake. Arrange piece on side of cake to resemble a cut branch, using a bit of remaining buttercream to glue piece to "log" and cover seam. Arrange shards of walnut brittle decoratively on cake. 

Cooks’ note:
Frosted cake (uncut and without brittle shards) can be made 3 days ahead and chilled, covered. Bring to room temperature before serving. Chill remaining buttercream, covered, then bring to room temperature before using. If buttercream seems lumpy, beat with electric mixer until smooth.  Makes 8 servings.

MAPLE MERINGUE BUTTERCREAM
We found that Grade A dark amber maple syrup (in addition to maple sugar) gave this frosting the deep, rich taste we wanted. Curiously, Grade B syrup, which is typically more robust than Grade A, didn’t give us as flavorful a result.

Beat egg whites with cream of tartar and salt in a large bowl with an electric mixer at medium speed until they just hold soft peaks. Add maple sugar 1 teaspoon at a time, beating, and continue to beat until whites just hold stiff peaks. Boil syrup in a small heavy saucepan over moderate heat, undisturbed, until it reaches soft-ball stage (registering 238 to 242*F on thermometer), about 3 to 7 minutes. Immediately remove from heat and slowly pour hot syrup in a slow stream down side of bowl into egg whites, beating constantly at high speed. Beat meringue, scraping down side of bowl occasionally with a rubber spatula, until meringue is cool to the touch, about 6 minutes. (It’s important that meringue be fully cooled before proceeding.)
With mixer at medium speed, add butter 1 tablespoon at a time, beating well after each addition. (If buttercream looks soupy after some butter is added, meringue is too warm: Chill bottom of bowl in a larger bowl of ice and cold water for a few seconds before continuing to beat in remaining butter.) Continue beating until buttercream is smooth. (Mixture may look curdled before all butter is added but will come together before beating is finished.)
Cooks’ notes:
• Buttercream can be made 1 week ahead and chilled, covered, or 1 month ahead and frozen. Bring to room temperature (do not use a microwave) and beat with an electric mixer before using.
• The egg whites in this recipe will not be fully cooked, which may be of concern if there is a problem with salmonella in your area. You may want to use either pasteurized egg whites in the carton or reconstituted powdered egg whites.  Makes about 3 cups.

Shake nuts in a sieve to remove nut powder (this will make for a clearer brittle.)
Line a baking sheet with nonstick pad or with an oiled sheet of foil.
Heat sugar and water in a deep 2-quart heavy saucepan over moderately low heat, stirring slowly with a fork, until melted and pale golden. Cook caramel without stirring, gently swirling pan, until golden. Stir in walnuts, then immediately pour caramel onto baking sheet, tilting sheet to spread caramel as thin as possible. Cool brittle completely at room temperature. Coarsely chop enough brittle to measure 1/2 cup, then break remainder into shards for decorating cake.
Cooks’ note:
Brittle can be made 1 week ahead and kept in an airtight container at room temperature. Makes about 2 cups (1/2 cup chopped plus shards).

Source:  Gourmet, Photo: Quentin Bacon