wash the fruit and strip the berries from the stem. Place in a saucepan with 500ml water. Heat gently and cook until the berries are very tender about 10 to 15 minutes.
Strain through a nylon sieve (see hints, tips and variations) pressing out as much fruit pulp as you can. Discard the seed and skin.
Place the fruit pulp in preserving pan or large saucepan and add the sugar. Heat gently, stirring frequently until all the sugar has dissolved.
Once all the sugar has been dissolved bring the mixture to a rolling boil and boil rapidly until setting point is reached. See below. This should take about 6–10 minutes.
Add the butter to the pan and stir to disperse any froth.
Pour into sterilised jars, cover and seal immediately. Label when cold
To test for set – Chill a couple of saucers before you start. After about 6 minutes boiling turn off the heat. Place a small amount of jam on the chilled saucer and allow to cool for a minute or two. Gently push with your finger tip. If the surface crinkles then setting point is reached. If not return the mixture to the boil and boil again for a further minute or so then test again. Repeat until setting point is reached To sterilise jar – Wash your jars and the lids in hot soapy water. Rinse and place upside down on a roasting tray while they are still wet. Place in a preheated oven at 160-180ºC for about 10 mins.