Bring cream to boiling in saucepan over medium-high heat. Remove from heat. Stir in chocolate until smooth. Stir in vanilla. Pour half into small bowl; refrigerate until good spreading consistency, 2 hours. Cover remaining half; let stand at room temperature to use as glaze.
Melt chocolate in small bowl set over hot (not boiling) water, or in small, heavy saucepan over very low heat. Let cool.
Heat oven to 350 degrees F. Grease bottom of 9-inch springform pan. Line bottom with waxed paper.
Sift flour, baking powder and salt onto piece of waxed paper.
Beat egg yolks and water in bowl until foamy. Gradually beat in sugar and vanilla; beat until thickened and light in color. Fold in flour mixture just until incorporated. Fold in cooled chocolate.
Using clean beaters and second large bowl, beat whites at high speed until soft peaks form. Gently fold into yolk mixture just until no streaks of white remain. Pour into prepared pan.
Bake in 350 degree F oven 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool in pan 10 minutes. Loosen edge with knife; remove side of pan. Cool on rack. Peel off waxed paper.
Bring marmalade to simmering in small saucepan. Press through fine sieve; discard solids. Stir in liqueur.
Trim cake to level top. Cut in half horizontally. Place top layer, cut side up, on platter. Brush top with marmalade. Place second layer on top, cut side down.
Spread refrigerated Chocolate Ganache over sides and top of cake, smoothing with long metal spatula to coat top and sides. Chill 1 hour. Makes 12 servings.