Place coffee filter in strainer set over medium bowl. Bring 1 1/2 cups water to boil in heavy medium saucepan.
Mix in coffee and tea. Turn off heat; cover and let steep 5 minutes. Strain mixture through coffee filter. Stir in Cognac. Cool completely.
Whisk yolks, cream, 4 tablespoons sugar, and salt in medium metal bowl to blend. Set bowl over saucepan of simmering waterand whisk until mixture is thick and thermometer registers 160°F, about 5 minutes.
Remove from over water.
Place over larger bowl of ice and water. Cool quickly, whisking often, about 5 minutes.
Stir mascarpone in large bowl to loosen texture. Fold in cooled yolk mixture in 3 additions, then fold in Cognac. Beat whites in medium bowl until soft peaks form.
Add 2 tablespoons sugar and beat until stiff but not dry; fold into sabayon in 3 additions. Cover; chill up to 1 day.
Combine pineapple, sugar, and salt in large nonstick skillet. Scrape in seeds from vanilla bean; add bean. Stir over medium heat until sugar melts and syrup forms. Continue cooking until syrup is absorbed and pineapple is dry and golden, stirring occasionally, about 10 minutes; cool completely.
Cover bottom of 13x9x2-inch glass baking dish with layer of ladyfingers.
Brush with coffee flavoring.
Spread with half of sabayon (about 3 cups). Scatter half of pineapple over. Repeat with ladyfingers, flavoring, sabayon, and pineapple. Cover; chill overnight.
Sprinkle tiramisù generously with grated chocolate and garnish with fresh pineapple, if desired.
Cut into squares or spoon onto plates and serve.
*An Italian cream cheese; sold at many supermarkets and at specialty foods stores and Italian markets.
