This is a really delicious marmalade and I do leave it bubbling away for way beyond the time mentioned, as I love the amber color and richer flavor that happens as it continues to simmer. Be careful you stir it a lot, so it doesn’t stick on the base of the pot.
I love to use my large copper pots for this recipe and often will double it but not in the same pan.

This recipe makes about 7-8 16oz jars marmalade

2 very heaped cups kumquats or Seville oranges, first washed in hot water then thinly sliced across, seeds removed, but keep seeds to the side and save. Put the seeds into some muslin tied up, as you will add the muslin bag to the fruit mixture as the seeds provide a lot of pectin which is necessary for the gel process.
2 1/2 oranges, (not Sevilles) finely sliced peel only
2 cups chopped orange pulp (seeded, with the seeds going into the muslin bag with the kumquat seeds)
1/3 cup freshly squeezed lemon juice
8 cups water
1 pinch of cayenne pepper
1 star anise
About 5 1/2 cups white sugar (you can experiment and add less if you like your marmalade more tart)
1 cup dark Muscovado sugar (This gives it it’s richness and amber color. Available on Amazon)

* Before anything, put all your clean jars, lids and other utensils you will use, into a long hot wash in the dishwasher, not opening it until you’re ready to put the marmalade into the jars. This keeps them sterile.
** Then put 3 small plates into the freezer to chill as you will need these to test if the “gel-ness” is ready for the marmalade

After prepping all the fruit, put the fruit, sliced orange peel, star anise, cayenne pepper, chopped orange pulp, lemon juice, kumquat and orange seeds in muslin and the water into your large pot, cover and let stand in a cool place for 48 hours.

Stir, bring to the boil, reduce the heat and simmer until the peel is tender, stirring. This will take up to 1 hour.
Add the sugars and stir until dissolved. Remove the star anise as the flavor is strong and you don;;t want it to overtake the kumquat flavor.
Boil to jellying point, about 2 to 2 1/2 hours if you want the darker marmalade.
Stir occasionally to prevent sticking.

This shows the darker color marmalade comparedd with the “normal” color.

To test if is at the gel point, have a couple of small plates in the fridge chilling and when you’re ready to test, take 1/2 tsp of the marmalade out and put it onto the cold plate. Put the plate in the fridge for 3 minutes and if it looks’feels gelatinous then it’s ready.
When ready, turn off the heat and skim off any foam from the surface.

Use a wide neck funnel (sterilized in the dishwasher too) to put the marmalade into the sterilized jars, it’s much less messy.
Leave 1/2 inch of headspace between marmalade and the top of the jar.
Screw on the canning lids.
Once the jars are sealed, store the marmalade away from direct light or heat. You may hear some popping of lids over the next few hours. This is good!
Once a jar is open, it must be stored in the refrigerator.
Sometimes the marmalade can take a week of two to “set” and gel properly, so don’t worry if it’s a little runny when you put it into the jars.