Preparation Line 8-inch-diameter cake pan with 2-inch-high sides with 3 layers of plastic wrap, overlapping sides of pan by 8 inches. Melt bittersweet chocolate, butter, and corn syrup in heavy medium saucepan over low heat, stirring until smooth. Remove from heat. Using electric mixer, beat eggs and sugar in large bowl until doubled in volume and pale yellow in color, about 3 minutes. Fold chocolate mixture into egg mixture (mixture will deflate). Pour mixture into prepared cake pan. Cover cake tightly with overhanging plastic wrap. Place steamer rack on bottom of large pot. Pour enough water into pot to almost reach bottom of steamer rack; bring to boil. Place cake on steamer rack. Cover pot and steam until tester inserted into center comes out with a few moist crumbs attached, adding more hot water to pot if necessary, about 2 hours. Remove cake from steamer. Refrigerate until cold and firm, at least 6 hours. (Cake can be prepared up to 3 days ahead of time. Keep refrigerated.) Slice cake with knife dipped into hot water and wiped dry. Top each serving with scoop of raspberry sorbet and serve immediately.
Preparation Line 8-inch-diameter cake pan with 2-inch-high sides with 3 layers of plastic wrap, overlapping sides of pan by 8 inches. Melt bittersweet chocolate, butter, and corn syrup in heavy medium saucepan over low heat, stirring until smooth. Remove from heat. Using electric mixer, beat eggs and sugar in large bowl until doubled in volume and pale yellow in color, about 3 minutes. Fold chocolate mixture into egg mixture (mixture will deflate). Pour mixture into prepared cake pan. Cover cake tightly with overhanging plastic wrap. Place steamer rack on bottom of large pot. Pour enough water into pot to almost reach bottom of steamer rack; bring to boil. Place cake on steamer rack. Cover pot and steam until tester inserted into center comes out with a few moist crumbs attached, adding more hot water to pot if necessary, about 2 hours. Remove cake from steamer. Refrigerate until cold and firm, at least 6 hours. (Cake can be prepared up to 3 days ahead of time. Keep refrigerated.) Slice cake with knife dipped into hot water and wiped dry. Top each serving with scoop of raspberry sorbet and serve immediately.