Prepare cake according to directions on package and bake in a greased 13 x 9-inch
Cut cake in half and save half for the next time. It will freeze well.
Melt chocolate in the top of a double boiler over hot, not boiling, water. Cool.
In a large bowl beat egg whites until soft peaks form. Set aside.
Beat butter with confectioners' sugar until light.
Add the egg yolks and beat until well blended and creamy. Add the cooled chocolate
and liqueur. Gently fold in beaten egg whites. Chill.
Use a clear trifle dish or a beautiful deep serving dish. Crumble half of the
cake and put it in the bottom of the serving dish. Spread a very, very thin layer
of raspberry jam over the top. Pour half of the chocolate mousse on top followed
by the Cool Whip.