I saw some Seville oranges at the supermarket the other day, and got them to make marmalade for my husband, who loves it. A quick surf on the internet turned up a recipe on the UK Thermomix site:
http://www.ukthermomix.com/recshow.php?rec_id=42The only thing that I did differently, was that rather than boiling the whole oranges in a pan on the hob before starting the TM instructions, I stuck them into the slow cooker / crock pot on high for an hour. Worked perfectly. Oh, also I did a larger batch than the recipe, so I needed to cook for longer. I did 2 batches - one of 450 g and one of 570 g. Cooked for 40 minutes and 50 minutes respectively. I didn't need to add any butter, it didn't froth. I seemed to have loads of peel, so I didn't put all of it in - just what looked right to me.
I have multiple jars of it now which look wonderful. Needs DH to comment on the taste, as I don't like orange marmalade - too bitter for me.