For the Sacher cubes, beat the egg whites with half the sugar until stiff. Cream the butter with the remaining sugar, gradually add the yolks and the softened chocolate.
Gently mix the beaten egg whites and flour and fold into the chocolate mixture. Pour the mixture into a greased and floured cake pan (20 x 24 cm) and bake at 180° C for about 1 hour. Cut the cooled Sacherkuchen once in the middle and spread with currant jam, assemble and cut into cubes of 2 x 4 cm. Spread the Sacher cubes with apricot jam and cover with chocolate icing.