Prepare brownie batter according to directions on box. Pour into a greased 13x9x2 inch pan. Bake according to instructions on box. When cool,cut into squares and remove from pan. Clean pan thoroughly and grease once more. Place brownies back into greased pan. Combine chocolate and coffee in top of double boiler, and melt over boiling water. Remove from heat. Beat egg yolks and stir in small amount of chocolate mixture; pour mixture into balance of chocolate mixture; stir until smooth.
Stir in liqueur and set aside to cool. Beat egg whites until foamy; gradually add sugar and beat until stiff. Whip cream until stiff. Fold cream into chocolate mixture; fold in egg whites. Pour filling over brownies. Cover with plastic wrap and chill 3 to 4 hours until firm. Invert onto serving platter and drizzle glaze. Let set and decorate with chocolate curls, if desired.
Directions for glaze: Combine chocolate and coffee in double boiler. Heat until melted. Stir well.