This chocolate sponge cake should be baked the same day you plan to assemble the roulade, because it will be easier to fill and shape.

　　

Ingredients

makes one 17-inch rolled cake

　　1/4 cup Dutch-process cocoa powder, sifted, plus more for dusting

　　1/4 cup all-purpose flour

　　1 tablespoon instant espresso powder

　　1 tablespoon hot water

　　6 large eggs, separated, room temperature

　　3/4 cup sugar

　　Mocha Mousse (page 393)

　　

Step 1

Preheat the oven to 325°F. Line a 17-by-12-inch rimmed baking sheet with parchment paper; set aside. Dust a large, clean kitchen towel with cocoa; set aside. Into a medium bowl, sift together the cocoa and flour. In a small bowl, stir together the espresso powder and the hot water until dissolved; set aside.

　　

Step 2

In the bowl of an electric mixer fitted with the whisk attachment, beat the egg yolks on high speed until thick and pale (they should hold a ribbon-like trail on the surface when the whisk is raised), about 5 minutes. Transfer to a large bowl; set aside.

　　

Step 3

With a clean bowl and whisk attachment, whip the egg whites on low speed until foamy. Raise speed to medium-high, and add the sugar in a slow, steady stream, beating until stiff peaks form.

　　

Step 4

With a rubber spatula, fold a third of the egg-white mixture into the egg-yolk mixture to lighten. Gently fold in remaining egg whites until just combined. Fold in the espresso mixture, then gradually fold in the cocoa mixture until just combined. Do not overmix.

　　

Step 5

Pour batter onto prepared sheet; using an offset spatula, spread evenly and smooth the top. Bake, rotating pan halfway through, until the cake springs back when lightly touched, 10 to 12 minutes. Immediately invert cake onto prepared towel; carefully lift off pan and peel off parchment paper. Starting on a long side, roll towel and cake into a log, incorporating the towel as you go. Transfer cake (still in towel), seam side down, to a wire rack to cool completely.

　　

Step 6

Unroll cake, leaving it on the kitchen towel. Using an offset spatula, spread Mocha Mousse evenly over the cake. Gently roll cake again into a log (do not incorporate towel). Wrap with the towel; refrigerate on a baking sheet until filling is well chilled, for at least 2 hours or up to 1 day. When ready to serve, generously dust roulade with cocoa; slice with a serrated knife.

　　Reprinted with permission from Martha Stewart's Baking Handbook by Martha Stewart. © 2005 Clarkson Potter