Preheat oven to 350ºF.
Grease and line an 8-inch round pan. Set aside.
In a large bowl, cream butter until light. Add the sugar and beat until smooth and fluffy. Beat in the yolks, then the melted chocolate. Add the flour and beat only until combined.
In a separate bowl, beat the egg whites until stiff. Fold the egg white mixture into the egg yolk mixture.
Pour into the prepared pan and bake for 45 minutes or until done. Cool.
Boil the strained marmalade. While warm, spread all over the cake.