Sunday, September 2, 2012
This raspberry roulade is a thin sheet cake spread with raspberry jam and whipped chocolate ganache, sprinkled with fresh raspberries, then rolled up and drizzled with chocolate. It's the chocolate lover's alternative to yesterday's Blueberry Roulade, and the ganache is crazy good.
You'll want to plan this cake in advance, since the whipped chocolate ganache needs to be chilled for hours. It can also be made a few days in advance. I've been leafing through Alice Medrich's Bittersweet, and I like her explanations for why chocolate behaves in a certain way, or her adaptations when using a chocolate with a higher or lower cacao percentage. One thing Medrich points out for this recipe is not to worry if the melted chocolate and cream look too soft to spread, because it won't stiffen until it's whipped -- and it will stiffen more after it's chilled.
For the sheet cake, from The King Arthur Flour Baker's Companion: The All-Purpose Baking Cookbook
¾ cup (3 ounces) unbleached all-purpose flour
¾ tsp baking powder
¼ tsp salt
4 large eggs, at room temperature
¾ cup (5¼ ounces) sugar
1 tsp vanilla extract
Whipped Chocolate Ganache Filling, adapted from Alice Medrich's Bittersweet
8 ounces bittersweet or semisweet chocolate, chopped medium-fine
1 cup heavy cream
½ cup (about 6 ounces) raspberry jam
1 cup fresh raspberries
Preheat oven to 400°. Line the bottom of a 10-by-15-inch jelly roll pan with parchment paper. [I used an 11-by-17-inch pan because it's what I already have, but you must reduce the baking time by 2 to 3 minutes.]
In a small bowl, sift together the flour, baking powder, and salt. Set aside.
In a large bowl, beat the eggs using the wire whisk attachment until foamy. Sprinkle in the sugar gradually, beating all the while, and continue beating until the batter is very thick and light lemon in color, 3 to 8 minutes. The batter will have doubled in volume. When the batter is sufficiently aerated it should fall from the beaters in a thick ribbon and mound on top of the remaining batter in the bowl temporarily, before being reabsorbed. Just before you stop beating the batter, add the vanilla.
Gently fold in the flour mixture, using a rubber spatula or whisk. Spread the batter evenly into the prepared pan.
Bake the cake for 12 to 14 minutes, until it's golden brown and springy to the touch. Remove the cake from the oven and invert it onto a (non-terry) dish towel that's been lightly sprinkled with confectioners' sugar. Peel off the paper, and using a knife or pizza wheel, trim the crust edges of the cake, if necessary. Starting with a short end, roll the cake and towel together into a log, and cool completely on a wire rack. Yes, it will cool while wrapped inside a towel, and fairly quickly too.
Make the ganache. Place the chopped chocolate in a medium bowl. Heat the cream in a heavy saucepan over medium-high heat until it comes to a gentle boil. Immediately pour the hot cream over the chocolate and stir until the chocolate is mostly melted. Let stand for 15 to 20 minutes to be sure all of the chocolate particles are completely melted.
Stir the ganache until perfectly smooth. Let cool. Cover the bowl and refrigerate the ganache for at least 6 hours or overnight; it must be very cold or it will curdle when it is whipped. The ganache can be prepared up to 4 days ahead.
When you are ready to use the ganache and not before, whip it until it is stiff enough to hold a nice shape and seems spreadable, but don't overdo. Overwhipped ganache looks granular, so watch it carefully. After whipping, the ganache will firm as it sits and even more after it is chilled, so spread it immediately. If you accidentally overwhip, or if the ganache becomes too stiff to spread, warm your spatula by rinsing it under hot tap water and wiping it dry as necessary.
Unroll the cake. Spread the jam on top of the cake, going all the way to the edges. Repeat with the whipped ganache. Sprinkle the raspberries on top of the whipped ganache. Re-roll the cake, without the towel this time, finishing with the seam side down. Slice the ends off for a better look. Sprinkle with confectioners' sugar or cocoa powder, or drizzle melted chocolate on top.