Preheat oven to 350 degrees. Grease and flour an 8- or 9-inch square baking pan. Set aside. Melt butter and chocolate over low heat or in the top of a double boiler over hot water. Remove from heat, add sugar and eggs, mix well. Sift together the flour, baking powder and salt. Stir into the chocolate mixture. Add the vanilla and pour the mixture into the prepared pan. Bake at 350 degrees for 25-30 minutes, until cake is baked but still very moist. Then cool. Remove the cake from the pan and cut into strips wide enough so they can line most of the side of a 2-quart souffle dish or charlotte mold. Cut strips through center to separate into two thinner halves. Lin the bottom and sides of diesh with the strips. Don't worry about piecing; the spaces won't show. Spoon the mousse filling into the cake-lined dish. Wrap the dish well, and chill overnight in the fridge or freezer. To serve, first defrost the cake, if frozen. Remove it from the pan, first loosening the sides with a knife, then dipping the pan partly into hot water to loosen the cake so it can be turned outonto a serving plate. Whip the cup of heavy cream until stiff and decorate top and parts of sides with cream. Serve in small slices.

Chocolate Mousse Filling: Melt the chocolate with the coffee over low heat or in top of double boiler over hot water. Remove from heat. Beat the yolks until pale in color, and stir them into chocolate. Stir in the coffee liqueur. Cool. Beat egg whites until stiff but not dry. Whip 1/2 c. cream until stiff. Fold the whites an the cream into the chocolate mixture.

12 servings.