Tiramisu Ice-cream Cake

* Note: Starbucks Dark Roast Espresso Swirl Ice Cream and Bryers All
Natural Coffee Ice Cream is recommended for this recipe. Make the Vanilla
Sponge Cake: Heat oven to 350 degrees. Butter a 9-inch-square baking pan.
Line pan with parchment paper, and butter again. Flour the pan, and set
aside. In a small bowl, sift together the flour and cornstarch; set aside.
In the bowl of an electric mixer fitted with the whisk attachment, beat the
egg yolks, vanilla, and 1/2 cup sugar on high speed until thick and pale,
about 5 minutes. Transfer the egg-yolk mixture to a large bowl. Wash and
dry the mixer bowl and the whisk attachment. Combine the egg whites and
salt in the mixer bowl, and beat on medium speed until whites hold soft
peaks, about 1 1/2 minutes. With mixer running, slowly add the remaining
1/4 cup sugar. Continue beating until stiff and glossy, about 1 minute.
Fold the egg-white mixture into the egg-yolk mixture. In three additions,
fold the reserved flour mixture into this new mixture. Transfer the batter
to the pan, and smooth the top with an offset spatula. Bake until a cake
tester inserted into middle comes out clean, 35 to 40 minutes. Transfer pan
to a wire rack to cool; turn out the cake, and wrap it in plastic wrap
until ready to use. (Makes one 9-inch square) Place sugar and 2/3 cup water
in a small saucepan. Bring to a boil over medium heat, stirring
occasionally. Remove from heat; stir in espresso and Kahlua. Let the syrup
cool. Using a serrated knife, cut the sponge cake in half horizontally,
making two layers. Place one layer in the bottom of a 9- by 9- by 2-inch
baking pan. Using a pastry brush, brush with 3/4 cup cooled syrup. Sift 2
tablespoons ground espresso over cake. Place espresso ice cream in the bowl
of an electric mixer. Beat on low speed with the paddle attachment until
spreadable. Spread ice cream over cake; top with second layer of sponge
cake. Brush with remaining syrup. Transfer cake to freezer for 20 minutes.
Remove cake from freezer; sprinkle with the remaining 2 tablespoons of
ground espresso. Place coffee ice cream in a mixer bowl. Beat on low speed
until spreadable. Spread ice cream over cake, forming large swirls. Return
to freezer; freeze until completely hardened. Meanwhile, make the Chocolate
Curls: Set a heatproof bowl, or the top of a double boiler, over a pan of
barely simmering water. Melt chocolate and shortening in bowl, stirring
occasionally. Divide chocolate between two 11- by 17-inch baking pans;
spread evenly with an offset spatula. Chill until your finger makes a mark,
but not a hole, when touching the chocolate. Remove pans from refrigerator.
Hold a sturdy metal pancake spatula at a 45-degree angle to pan; scrape
away from you, forming curls. If chocolate is too brittle, quickly wave pan
over top of warm stove. If too soft, briefly return to refrigerator. (can
be refrigerated in an airtight container up to 2 weeks) To serve, garnish
with chocolate curls. Serves 12.