Ingredients
For the Chocolate Genoise Roll- 3 large eggs
- 3 large egg yolks
- Pinch of salt
- 3/4 cup sugar
- 1/3 cup cake flour
- 1/3 cup cornstarch
- 1/4 cup Valrhona cocoa powder
- 4 ounces bittersweet chocolate
- 2/3 cup heavy cream
- 2 cups heavy cream
- 1 teaspoon Cognac (optional)
- Sugar or vanilla sugar, to taste
- 1–2 tablespoons of reserved chocolate ganache (from the icing)
- 2 large egg whites
- 1/4 teaspoon cream of tartar
- 1/2 cup superfine sugar
- Cocoa powder, for dusting
Instructions
Line a jelly-roll pan with parchment paper. Butter the paper and dust it lightly with flour.
Set a rack in the center of the oven and preheat to 400°F.
Fill a medium saucepan halfway with water and bring it to a simmer.
In the bowl of a stand mixer, whisk together the eggs, yolks, salt, and sugar.
Set the bowl over the pan of simmering water and gently whisk until the mixture is just lukewarm to the touch.
Attach the bowl to a stand mixer fitted with the whisk attachment. Beat on medium-high speed until the mixture is pale, tripled in volume, and completely cool—this should take about 5 minutes.
While the eggs are whipping, whisk together the flour, cornstarch, and cocoa powder in a separate bowl.
Sift one-third of the dry mixture over the whipped eggs and gently fold it in with a rubber spatula, making sure to scrape the bottom of the bowl to avoid flour pockets.
Repeat with the second and final thirds of the flour mixture, folding gently after each addition to maintain the batter’s volume.
Pour the batter into the prepared pan and spread it evenly with an offset spatula.
Bake for 9–10 minutes, or until the cake is well-risen, lightly springy to the touch, and no longer shiny. Be careful not to overbake, as it will make the cake difficult to roll.
Lay a clean kitchen towel on your work surface and sprinkle it lightly with sugar.
Run a paring knife along the edges of the pan to loosen the cake, then carefully invert it onto the sugared towel.
Peel off the parchment paper, let the cake sit for a minute right-side up, then gently roll it up with the towel (starting from the long edge) while it’s still warm.
Let it cool completely in the rolled shape—this helps set the form and prevents cracking when filled.
Chocolate Ganache Icing
Chop the chocolate into small, even pieces and place it in a medium heatproof bowl.
Heat the cream in a small saucepan over medium heat until it just begins to simmer—bubbles should appear around the edges, but do not let it boil.
Combine the hot cream with the chocolate. Pour the cream over the chocolate and let it sit undisturbed for 5 minutes to allow the chocolate to soften. Stir gently until the mixture is smooth and glossy.
Chill the ganache in the refrigerator, stirring occasionally, until it's cool and spreadable but not fully solidified.
Cream Filling
In a chilled mixing bowl, beat the heavy cream until soft peaks form. Add Cognac and sweeten to taste with sugar or vanilla sugar. Add a spoonful of chocolate ganache for extra richness and flavor. Continue beating until stiff peaks form. Be careful not to overwhip.
Meringues Mushrooms
Preheat the oven to 225°F. Line two baking sheets with parchment paper or silicone mats.
In the bowl of a stand mixer fitted with the whisk attachment, beat the egg whites on low speed for 1 minute, until foamy. Add the cream of tartar and continue beating on medium speed for 1–2 more minutes, until soft peaks form.
Increase the speed to medium-high and gradually add the sugar. Beat for about 5 more minutes, until the meringue is glossy and holds stiff peaks.
Fit a piping bag with a ½-inch round tip and fill it halfway with meringue. Twist the top of the bag and pipe ½-inch rounds onto one of the prepared baking sheets, spacing them about 1 inch apart—these will be the mushroom caps.
Refill the bag with the remaining meringue and pipe the stems onto the second baking sheet. Start each stem with a slightly wider base, tapering upward into a cone shape. Try to make an even number of caps and stems; adjust as needed near the end.
Lightly wet your fingertip and smooth the tops of the mushroom caps, if needed. (No need to smooth the stems—you’ll trim them later.)
Bake for 1½ to 2 hours, or until the meringues are dry and crisp but not browned. Let cool completely on the baking sheets.
Trim about ¼ inch off the pointed ends of the stems using a serrated knife, creating a flat base for attaching the caps or if the base has a point, make carve out a hole in the top so they can sit on top of each other. Attach buy using some of the ganacee melted chocolate.
Finish by dusting the tops of the mushrooms with cocoa powder for a realistic touch.
Other Decorations Ideas
- Marzipan Mushrooms: Roll half of the marzipan into balls for the caps and half into cylindrical lengths for the stems.
- Holly leaves: Knead greed color into marzipan and use cutter to cut out leaves.
- Holly berries: Knead red color into a tiny piece of marzipan. Roll into tiny balls.
- Pine cones: Knead chocolate into marzipan. Form cone shape and use scissors to slash sides of the cones.