CRUST
2/3 c  Chocolate wafer crumbs
1/3 c  Graham cracker crumbs
1/4 c  Unsalted butter; melted

–DARK CHOCOLATE MOUSSE–
4 oz Semi-sweet chocolate
– finely chopped
2 oz Unsweetened chocolate
– finely chopped
6 Egg yolks
3/4 c Sugar
1/2 c Frangelico liqueur
1 1/4 c Chilled whipping cream

–WHITE CHOCOLATE MOUSSE–
3/4 c Whipping cream
10 oz White chocolate; chopped
3 tb Frangelico liqueur
1 1/3 c Whipping cream; chilled
2 oz Semisweet chocolate
– coarsely chopped
1 tb Unsalted butter

FOR CRUST: Preheat oven to 350F. Mix all crumbs in bottom of 9-1/2-inch
springform pan. Pour butter over. Mix with fork until well-blended. Press
mixture firmly onto bottom of pan. Bake 8 minutes. Cool crust on rack. FOR
DARK CHOCOLATE MOUSSE: Stir both chocolates in double boiler over barely
simmering water until smooth and melted. Cool to lukewarm. using electric
mixer, beat yolks to blend in large bowl. Gradually add sugar and beat
until pale yellow and slowly dissolving ribbon forms when beaters are
lifted. Blend in Frangelico, then melted chocolate. Whip cream in another
bowl until soft peaks form. Fold 1/3 of cream into chocolate mixture.
Gently fold in remaining cream. Pour mixture into crust; smooth top. Freeze
until set, about 30 minutes. FOR WHITE CHOCOLATE MOUSSE: Bring 3/4 cup
cream to boil in heavy small saucepan. Reduce heat and simmer 2 minutes.
Finely chop white chocolate in processor. Pour hot cream through feed tube
and blend until mixture is smooth, about 1 minute. Transfer to medium bowl.
Cool completely.

Stir Frangelico into white chocolate mixture. Using electric mixer, whip 1
1/3 cups cream in medium bowl until peaks form. Fold 1/3 cream into white
chocolate mixture. Gently fold in remaining cream. Pour over dark chocolate
mousse; smooth top. Freeze until top of mousse sets.

Cover mousse and freeze at least 24 hours. Run knife around edges of pan
to loosen. Release pan sides from mousse. Smooth sides of mousse with
icing spatula. Return to freezer.

Stir 2 ounces of semisweet chocolate and butter in heavy small saucepan
over low heat until melted and smooth. Cool to lukewarm. Spoon into
parchment cone or pastry bag fitted with small plain tip. Pipe chocolate in
decorative pattern around edge of mousse. Freeze until chocolate sets,
about 10 minutes. (Can be prepared 2 days ahead. Cover with plastic wrap.)
Cut frozen mousse into wedges to serve.