The unusual flavoring for this cake is lemon zest. It is used in both the light, moist cake and the milk chocolate ganache and it delicately perfumes and complements both. Lemon zest, which is rich in the essential oil of lemon, transmits a lemon perfume without any of the acidity of lemon juice, which would mar the chocolate flavor.

Makes one 9-inch layer cake, about 12 servings


2 1/4 cups cake flour
3 teaspoons baking powder
1/2 teaspoon salt
8 tablespoons (1 stick) unsalted butter, softened
1 1/2 cups sugar
2 teaspoons finely grated lemon zest
1/2 teaspoon lemon extract
1/2 cup (about 4 large) egg whites
1 1/4 cups milk


Zest of 2 lemons, removed in long strips with a vegetable peeler
2 cups heavy whipping cream
4 tablespoons (1/2 stick) unsalted butter, softened
20 ounces milk chocolate, cut into 1/4-inch pieces
4 ounces bittersweet chocolate, cut into 1/4-inch pieces

Two 9-inch round pans, 1 1/2 to 2 inches deep, buttered and lined with buttered parchment or wax paper

  1. Set a rack at the middle level of the oven and preheat to 350 degrees.
  2. To make the cake, sift the cake flour, baking powder and salt onto a piece of parchment or wax paper and set aside.
  3. Use an electric mixer set at medium speed to beat the butter and sugar until light, about 3 minutes. Beat in the lemon zest and extract.
  4. In a bowl, whisk together the egg whites and milk.
  5. Add a third of the flour mixture to the butter and sugar mixture and beat until smooth. Scrape down bowl and beaters. Beat in half the milk and egg white mixture until incorporated, then beat in another third of the flour mixture. Scrape bowl and beaters. Beat in remaining liquid until absorbed, followed by remaining flour mixture. Scrape well after each addition.
  6. Divide batter evenly between prepared pans and smooth top. Bake until cake is well risen and a toothpick inserted in the center emerges clean, about 30 to 35 minutes. Cool layers in pans for 5 minutes, then invert to racks to cool. Peel off paper. (Layers can be double-wrapped in plastic wrap and chilled for several days or frozen.)
  7. To make the ganache, place the pieces of zest in a saucepan and add the cream. Bring to a simmer over low heat. Remove from heat and allow zest to steep about 5 minutes. Remove zest from cream with a slotted spoon and discard. Add butter to the cream and bring to a boil over low heat. Remove from heat and add both types of chocolate. Shake pan to submerge chocolate and allow to stand 5 minutes. Whisk until smooth, then cool to room temperature. Ganache will thicken to spreading consistency.
  8. To finish, place one cake layer right side up on a platter or cardboard. Place ganache in mixer bowl and beat with paddle until light, about 20 seconds. Using an offset spatula, about a third of the ganache over the cake layer. Place the other cake layer upside down on the ganache, so that the smooth bottom of the cake layer is on top. Spread the top and sides of the cake evenly with the remaining ganache.