Remove any pips and blitz the elderflower infused fruit. Reserve 1 cup.
Place the thinly sliced orange peel in a pot with one cup of water and boil for 10 minutes. Strain and discard the water.
Place the fruit pulp and cooked orange peel into a clean pot with 4 cups of water. Boil for 10 minutes and place in the fridge for 12 hours or overnight.
For every cup of liquid add 1 cup of sugar.
Bring to a boil until all the sugar has dissolved. Stir constantly.
Place a saucer in the freezer.
Once the sugar has dissolved bring to a rolling boil, and check for a jam consistency. Place the liquid on the saucer from the freezer. Run your finger through the middle of the marmalade puddle. If the liquid does not re-join - it is ready to place in sterilised jars. If it does join boil for another 2-3 minutes and try again.
Ladle hot marmalade into hot sterlasied jars (see the blog post for my method on sterilising jars). Leave a 5mm gap (1/4 inch) from the top of the jar. Clean any sticky marmalade from the screw band and place on the lid.
Leave the filled jars on the bench to cool. Listen for a pop to know when the jar seals itself.