Instructions: For Filling:
Line 5 1/2- to 6-cup metal loaf pan with plastic wrap, overlapping sides.

Melt chocolate and butter with corn syrup in heavy large saucepan over medium-low heat, stirring until smooth. Cool to lukewarm, whisking occasionally.

Whisk 1/4 cup cream, 4 tablespoons Frangelico, yolks, sugar and 2 tablespoons water in small metal bowl. Set bowl over saucepan of simmering water and whisk constantly until candy thermometer registers 160F., about 3 minutes. Remove from over water. Add yolk mixture and remaining 2 tablespoons Frangelico to chocolate mixture in pan; whisk until smooth. Mix in nuts. Chill until cool, about 10 minutes. Using electric mixer, beat remaining 1/4 cup cream with sour cream in large bowl

to stiff peaks. Add chocolate mixture and fold together. Pour filling into prepared pan; smooth top. Cover and chill overnight.

For Glaze:
Combine all ingredients in heavy medium saucepan. Stir over low heat until melted. Cool to lukewarm. Pour 1/2 cup glaze over filling in pan; shake pan gently to smooth top. Freeze until glaze sets, about 20 minutes.

Line cookie sheet with foil. Lift loaf from pan. Turn loaf out onto foil; peel off plastic. Whisk remaining glaze over low heat until just spreadable. Pour all but 1/4 cup glaze over loaf. Spread over top and sides with icing spatula, spreading glaze that runs onto foil up sides of loaf to cover completely. Chill 1 hour. (Can be prepared 2 days ahead.

Cover and chill loaf and reserved 1/4 cup glaze separately.)

For Sauce:
Bring half and half to simmer in heavy medium saucepan. Scrape in seeds from vanilla bean; add bean. Whisk yolks and sugar in medium bowl to blend. Whisk in hot half and half mixture. Return mixture to saucepan and stir over medium-low heat until custard thickens and leaves path on back of spoon when finger is drawn across, about 5 minutes; do not boil.

Strain into bowl. Mix in cream and Frangelico. Cover and chill until cold. (Can be prepared 2 days ahead.)

Melt milk chocolate in top of double boiler over simmering water, stirring

until smooth. Spoon all but 2 tablespoons melted chocolate into parchment

cone. Remove loaf from foil and transfer to platter. Pipe chocolate lines crosswise atop loaf, spacing 1/8 inch apart. Dip 1 hazelnut halfway

into chocolate in pan; place atop center of loaf. Repeat with remaining nuts, spacing evenly and forming line down center. (Can be prepared 3 days ahead; refrigerate.)

Using long thin knife, cut loaf into 1/2-inch-thick slices, wiping knife clean between cuts. Place slices on plate; surround with sauce. Whisk reserved glaze over low heat until melted. Spoon into parchment cone.

Pipe Zs atop sauce.

Serves 12.

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