For the cocoa souffle sheet and filling:
1 quart good quality coffee frozen yogurt or low fat ice cream
6 large eggs, separated
1 teaspoon vanilla extract
3/4 cup sugar
1/4 teaspoon cream of tartar
1/4 cup Dutch Process cocoa
Additional cocoa for dusting
For the meringue topping:
1/4 teaspoon cream of
tartar
3 teaspoon water
1/2 cup sugar
3 egg whites
2 tablespoons powdered sugar
Bittersweet Chocolate Sauce, optional
Equipment:
Two 17 1/2 x 11 1/2 inch jelly roll pans
Instant read thermometer
14 x 4 inch piece of corregated cardboard wrapped in foil
Form the sheet of frozen yogurt: Line the
bottom and sides of one of the pans with aluminum foil. If the frozen yogurt is
rock hard, refrigerate it briefly until softened slightly; it must be scoopable
but still very firm. (Note that frozen yogurt melts much more quickly than ice
cream, so it must be very firm when you begin to work with it.) Distribute
scoops of yogurt all over the pan. Working quickly and leaving about 4 inches at
one end of the pan uncovered, spread the yogurt evenly in the pan by mashing the
scoops with the back of a large spoon and pushing them together. Cover with foil
and freeze at least several hours or until needed.
Make the cocoa souffle sheet: Position
the rack in the lower third of the oven and preheat to 350 degrees F. Line the
bottom of the second pan with a piece of parchment or wax paper.
In a large bowl, beat the egg yolks with vanilla and 1/2 cup of the sugar
until pale and thick. Set aside.
In a separate mixing bowl, with clean dry beater, beat the egg whites and
cream of tartar on medium speed until soft peaks form. Gradually sprinkle in the
remaining sugar, continue to beat at high speed until stiff but not dry. Mix a
quarter of the egg whites into the yolk mixture to lighten it. Scrape the
remaining whites into the bowl and sift the cocoa over them. Fold until
completely incorporated.
Spread the batter evenly in the pan and bake until the pastry springs back
when gently pressed with fingertips, 12 to 15 minutes. Cool completely, in the
pan on a wire rack.
Sprinkle a large sheet of foil with cocoa. Run a small knife or metal spatula
around the edges of the cocoa pastry to detach it from the pan. Invert the cocoa
pastry onto the foil sheet. Remove the pan and peel the paper pan liner from the
cocoa pastry.
Assemble the roll: Remove the sheet of
frozen yogurt from the freezer and remove the foil covering. Center and invert
the yogurt sheet on top of the cocoa souffle sheet. Remove the pan and the foil.
The long edges should be lined up and but there should be 2 inches of cocoa
souffle exposed at each end.
Fold the exposed pastry over the yogurt at one end of the sheet. Continue to
roll the pastry and yogurt up together, using the foil underneath as an aid as
necessary. Do not worry if there is some initial cracking as you roll, however,
if the yogurt is much too stiff to roll, wait a few minutes until it is pliable.
Wrap the roll in foil and return to the freezer overnight or until hard.
Preheat the oven to 425 degrees F.
Make the meringue topping: Bring 1-inch
of water to a simmer in a large saucepan. Combine the water, cream of tartar and
sugar in a 6 to 8 cup stainless bowl. Whisk in the egg whites. Place thermometer
near stove in a mug of very hot tap water. Set bowl in saucepan. Stir mixture
briskly and constantly with a rubber spatula, scraping the sides and bottom
often to avoid scrambling the egg white. After 1 1/2 minutes, remove the bowl
from the skillet. Quickly insert thermometer, tilting bowl to cover stem by at
least 2 inches. If less than 160 degrees F, rinse thermometer in simmering
skillet water and return it to mug. Replace the bowl in skillet. Stir as before
until temperature reaches 160 degrees F when bowl is removed. Beat on high speed
until cool and stiff. Set aside.
Remove the frozen roll from the freezer and unwrap it. Place the roll on the
foil wrapped cardboard. Use a metal spatula to cover the roll completely with a
thick coating of meringue topping. Leave no cake exposed and be sure that the
meringue touches the foiled cardboard all along the base of the roll. Use a fork
to texture the meringue to resemble tree bark. Transfer the buche on its foiled
base to a baking sheet. Sieve powdered sugar over the buche. Bake just until
golden, 4 to 6 minutes, watching carefully. Slide a wide spatula or pancake
turner under the foiled cardboard and transfer the buche to a serving platter.
Serve immediately with Bittersweet Chocolate Sauce, if desired.
Prep Time: 12 hours
Cook Time: 1 hour 30 minutes
Difficulty: Easy
