Make truffles: Bring cream to boil in heavy medium saucepan. Remove from heat. Add chocolate; whisk until chocolate melts and mixture is smooth. Mix in whiskey. Chill until mixture is cold and firm, at least 2 hours.
Drop truffle mixture by tablespoonfuls onto waxed paper. Line baking sheet with foil. Roll each chocolate drop between palms into ball (if truffle sticks to hands, dust hands with unsweetened cocoa powder); place on baking sheet. Freeze until hard, about 1 hour; then cover. (Can be prepared 1 week ahead. Keep frozen.)
Make sauce: Place cream in small bowl. Scrape seeds from vanilla bean. Mix seeds and bean into cream.
Stir sugar and water in heavy medium saucepan over low heat until sugar dissolves. Increase heat and boil without stirring until syrup turns deep amber color, brushing down sides of pan with wet pastry brush and swirling pan occasionally, about 10 minutes. Remove from heat; add cream (mixture will bubble vigorously). Return pan to low heat; stir until caramel is smooth. Boil until color deepens and caramel thickens, stirring occasionally, about 2 minutes. Strain caramel into small bowl. Chill sauce. (Can be prepared 1 week ahead. Cover and keep refrigerated.)
Make soufflés: Whisk yolks to blend in medium bowl; set aside. Whisk 1/4 cup sugar, cornstarch and cocoa in medium stainless steel bowl until no cornstarch lumps remain. Whisk in milk. Add chocolate and butter. Scrape in seeds from vanilla bean; add bean.
Place bowl with chocolate mixture over saucepan of simmering water (do not allow bottom of bowl to touch water). Whisk until mixture is smooth, about 2 minutes. Remove from over water. Gradually whisk some of hot chocolate mixture into yolks. Whisk yolk mixture back into bowl with chocolate mixture.
Place over simmering water. Whisk until smooth and thickened to pudding consistency, about 4 minutes. Remove from over water. Gradually mix in whiskey. Remove bean; cool to lukewarm.
Preheat oven to 450°F. Butter eight 2/3- to 3/4-cup soufflé dishes or custard cups; dust with sugar. Arrange dishes on baking sheet. Place 1 truffle in each dish.
Using electric mixer, beat whites in medium bowl until soft peaks form. Gradually add 2 tablespoons sugar, beating until stiff but not dry.
Fold whites into lukewarm soufflé base in 2 additions. Divide soufflé mixture among prepared dishes, filling almost to top. (Can be prepared 1 week ahead. Cover dishes with foil and freeze. Uncover but do not thaw before baking.) Place soufflés on baking sheet in oven; reduce temperature to 400°F. Bake until puffed and dry-looking on top, about 17 minutes for unfrozen or 22 minutes for frozen.
Transfer dishes to plates. Sift powdered sugar over. Serve, passing cold caramel sauce separately.