Dark Seville Orange Marmalade

In a large pot in 1 litre water, bring whole oranges to a boil and simmer for about one hour or until very soft. Lift out oranges from cooking water with a slotted spoon, cut them in half, and spoon out inside. In another pot, in 1/2 litre water, bring the pulp to a boil and simmer about 10 minutes. Drain and put liquid aside. (I used a Foley food mill to press the juice from the pulp, it did a fine job!) Meanwhile, thickly slice soft orange peels and return peels into their cooking water. Add sugar, grated peel and the drained liquid of pulp and the molasses. Slowly bring to a boil under constant stirring, until sugar dissolves. Simmer 20 to 60 minutes or until jelly forms. Cool for about 20 minutes, (add liqueur if desired) pour into sterilized jars and seal immediately. Note: I cheat on the sugar - use only 2 kg, and add some pectin. It still comes out delicious.