Lightly grease 8x4 inch loaf pan; line bottom and sides with waxed paper. Melt chocolate with water in saucepan over low heat, stirring constantly. Cool slightly. Beat cream cheese and sugar until smooth. Beat in vanilla and chocolate mixture. Fold in 3 C of the La Creme. Stir in milk. Spread into lined pan. Chill until firm, about 4 hours. Unmold and remove waxed paper. Add liqueur to remaining La Creme. Cut terrine into slices and serve with topping mixture.