Chocolate Truffle Cake

Assemble the cake at least 1 day before serving so the layers can firm in the refrigerator.

Ingredients for the chocolate orange cake:
1 1/4 cups unbleached all purpose flour
1 cup superfine sugar
1/2 cup Dutch-processed cocoa powder
2 teaspoons baking powder
1/4 teaspoon fine sea salt
1 1/2 cups heavy cream
grated zest of 1/2 orange
3/4 teaspoon pure vanilla extract
2 large eggs, beaten

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Ingredients for the orange syrup:
2/3 cup simple syrup (see end)
1 T orange-flavored liqueur, such as Grand Marnier

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Ingredients for the whipped ganache:
2 1/4 cups heavy cream, divided 14 ounces semisweet or bittersweet chocolate
(no more than 62 percent cacao), finely chopped

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Ingredients for the chocolate glaze:
3/4 cup heavy cream
2 T freshly brewed espresso or
1 1/2 teaspoons instant espresso powder dissolved in 2 T boiling water
2 T superfine sugar
8 ounces semisweet or bittersweet chocolate (no more than 62 percent cacao), finely chopped
2 T light corn syrup
chocolate pearls, for garnish

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Ingredients for simple syrup:
1 cup granulated sugar
1 cup water

Preparing the simple syrup:
Combine the sugar and water in a small saucepan. Bring to a boil over medium heat, stirring constantly.

Stop stirring and boil for 1 minute. Cool completely. (The syrup can be stored in a covered container and refrigerated for up to 2 months.)

Makes about 1 1/3 cups

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Preparing the cake:
Position a rack in the center of the oven and preheat to 350 degrees F. Line a half-sheet pan with a silicone baking mat, or lightly butter the pan and line the bottom with parchment paper.

Sift the flour, sugar, cocoa, baking powder, and salt together. Combine the cream, zest, and vanilla in the bowl of a heavy-duty stand mixer. Attach the bowl to the mixer and fit with the whisk attachment. Whip on medium speed until the cream holds its shape, just before soft peaks begin to form. Gradually beat in the eggs-the mixture will thin somewhat. Change to the paddle attachment. On low speed, add the flour mixture, and beat until smooth, scraping down the sides of the bowl, about 1 minute. Because the cream is chilled, the batter thickens to the consistency of very stiff frosting. Distribute the batter in 5 large dollops in the pan, 1 in each corner and 1 in the center. Spread evenly with an offset metal spatula.

Bake until the cake springs back when pressed gently with your finger in the center, about 15 minutes. Transfer to a wire rack and let cool completely. Run a knife around the inside of the half-sheet pan to loosen the cake. Place a large piece of parchment paper over the cake, then top with a large cutting board. Invert the pan and board together, and remove the pan and mat. Cover the cake with plastic wrap and refrigerate to chill and firm, at least 1 hour and up to 1 day before using.

The cream in this cake makes a very tender crumb that can break when handling. Refrigerate the unmolded sheet cake until the cake is chilled and firm, and the cut rounds will be sturdier and ready for stacking.

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Preparing the orange syrup:
Stir the simple syrup and liqueur together.

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Preparing the whipped ganache:
Bring 3/4 cup plus 2 tablespoons of the cream to a simmer in a medium saucepan over medium heat. Put the chocolate in a heatproof bowl. Add the hot cream and let stand until the chocolate softens, about 3 minutes. Whisk until smooth. Let cool until tepid but still fluid, about 15 minutes.

Whip the remaining 1 1/4 cups plus 2 tablespoons cream in the chilled bowl of a heavy-duty stand mixer fitted with the whisk attachment on medium speed only until the cream holds its shape, just before soft peaks begin to form. Pour the whipped cream over the cooled chocolate mixture and fold together with a silicone spatula. Do not overmix, or the ganache will be grainy. Transfer 1/2 cup of the ganache to a small bowl and set aside.

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Assembling the cake:
Transfer the cake, with its cutting board, to the work surface. Using an 8 by 3-inch metal cake ring as a template, cut out two 8-inch rounds of cake from opposite corners of the chocolate cake. Cut out two half-rounds of cake from the remaining cake, and save the scraps. The two half-rounds will be put together, with the reserved scraps cut to fill in the gap, to become the center cake layer.
Place the cake ring on a half-sheet pan. Insert an 8-inch cardboard round, white side up, inside the ring. Place a whole cake layer in the ring, and drizzle and brush with about 3 1/2 tablespoons of the syrup. Top with half of the whipped ganache filling, and spread evenly. Top with the partial cake layers, and fill in the gap with trimmings of the reserved cake scraps. Top with a smaller cardboard round and press gently to level the layers. Remove the cardboard round. Drizzle and brush the layer with another 3 1/2 tablespoons syrup. Spread with the rest of the filling. Add the final cake layer, cover with the smaller cardboard round, and press gently to level the layers.

Remove the cardboard round. Drizzle and brush the cake with the remaining syrup. Using a small offset spatula, spread the reserved 1/2 cup filling over the top cake layer to make a smooth surface that fills any small holes. Refrigerate the cake until completely chilled, at least 6 hours or overnight.

Remove the cake from the refrigerator. Place on the work surface. Rinse a kitchen towel under hot water and wring it out. Wrap the hot, moist towel around the sides of the cake ring, being careful not to get water on the top of the cake. Let stand for about 30 seconds. Lift up on the ring to remove it. (If it doesn't remove easily, moisten the towel again and reapply to the sides.) Place the cake on a small round wire cake rack set on a half-sheet pan. Using a small offset spatula rinsed under hot water and dried, smooth the sides of the cake to even out the exposed ganache between the layers. Refrigerate the cake on the rack until the outer layer of ganache is very firm, about 30 minutes.

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Preparing the glaze:
Bring the cream, espresso, and sugar just to a simmer in a small saucepan over medium heat. Remove from the heat and add the chocolate. Let stand until the chocolate softens, about 3 minutes. dd the corn syrup and stir well with a silicone spatula until the chocolate is melted and the glaze is smooth. Do not whisk, as this will create bubbles that will mar the surface of the glaze. Strain into a 2-cup glass measuring cup. Let stand until tepid but still liquid and pourable, about 15 minutes.

Transfer the cake on its wire cake rack to a room-temperature half-sheet pan. About 1 inch from the top edge of the cake, pour some of the glaze in a circle around the outside edge of the cake. Pour the remaining glaze in the center of the cake. Using a large offset metal spatula, quickly smooth the glaze over the top of the cake, letting the excess run down the sides. If needed, use the spatula to scrape up the glaze on the pan, and pour it back over the top of the cake to fill in any unglazed areas. Transfer the cake on the rack to a clean half-sheet pan. Refrigerate until the glaze sets, at least 1 hour. (The cake can be made up to 1 day ahead, covered with a cake dome, and refrigerated.) Lightly press small handsful of the chocolate pearls along the bottom edge of the cake. Transfer the cake to the serving dish, and sprinkle more along the top edge of the cake, letting them fall randomly on the plate. Slice the cake with a sharp knife (dipped in hot water and wiped dry before each cut).

Serves 12