Chocolate Terrine

Line 9 x 5 inch rectangular loaf pan with 2 pieces parchment extending 1 inch over sides. Melt chocolate with butter in top of double boiler over barely simmering water, stirring until smooth. Remove from heat. Cool 5 minutes. Whisk in yolks one at at a time. Beat egg whites until soft peaks form. Gradually add sugar and beat until stiff but not dry. Fold half of whites into cooled chocolate. Gently fold in remaining whites. Pour mousse into prepared pan. Cover with plastic and refrigerate overnight. Finely grind hazelnuts. Blend in flour and sugar. Add butter and cut in until mixture has sandy texture. Blend in yolk and enough cream to form dough. Gather dough into square, flatten into rectangle. Wrap in plastic and refrigerate one hour. Preheat oven to 350F. Roll dough out between sheets of parchment to a 9 x 5 inch rectangle. Peel off top sheet. Transfer to cookie sheet. Bake until firm and beginning to brown, about 15 minutes. Cool pastry on sheet. Refrigerate one hour. Melt chocolate and butter with corn syrup in heavy medium saucepan over low heat, stirring until smooth. Scald cream with Cognac in heavy small saucepan. Pour into chocolate; mix well. Cool slightly. Carefully place pastry atop mousse. Place cake rack over terrine. Invert terrine onto rack. Peel off parchment. Carefully cut away any excess pastry. Place terrine on rack over cookie sheet. Pour lukewarm glaze over terrine, spreading gently to coat top and sides. Arrange nuts down center of terrine. Chill until glaze sets. Transfer terrine to serving plate. Cut into slices using warm knife. Transfer to plates. Spoon custard around each piece and serve. Vanilla Custard Sauce 2 cups half and half 2/3 cup whole milk 1 vanilla bean, split lengthwise 5 egg yolks 2/3 cup sugar Combine half and half and milk in medium saucepan. Scrape in seeds from vanilla bean, add pod. Bring to simmer. Remove from heat. Cover and let steep for 40 minutes. Whisk yolks, sugar and salt in medium bowl to blend. Bring half and half mixture to boil. Whisk a small amount milk into yolks. Return mixture to saucepan and stir over medium-low heat until custard thickens, about 10 minutes; do not boil. Strain into bowl. Cover and refrigerate until well chilled.