Recipe by Neven Maguire

Ingredients

Makes about eight jars

1.8kg blackberries

1.5kg jam sugar (the one with added pectin)

Juice and rind of 1 lemon

2 tbsp cassis

Finger-tip size knob of butter (optional)

  • The night before you make your jam, layer the berries and sugar together in a very large bowl, then cover and set aside at room temperature. This helps the sugar to start dissolving so you don't run the risk of over-cooking the fruit when you actually begin to make the jam. The next morning, give everything a quick stir, then set aside again until you are ready to start cooking.
  • Before you start, put a small saucer in the freezer. Tip the berries, scraping out all juices and any undissolved sugar, into a preserving pan, or a large, wide-based pan (the wider and more open the pan, the faster the jam will be ready so a preserving pan is really ideal). Stir in the lemon juice and cassis.
  • Start the berries over a low heat until all the sugar is completely dissolved, then bring to the boil and simmer for fi ve minutes. Turn off the heat and spoona little hot syrupy jam onto the chilled saucer. Once cool, push the jam with your finger. If it wrinkles a little, it's ready and has reached setting point. If it is too runny to wrinkle, return the pan to the heat and boil in two to three minute stages, removing the pan from the heat each time you do the saucer check, until the jam wrinkles. Skim off any excess scum, then stir in the knob of butter, if you are using it (this will help to dissolve any remaining scum). Leave the jam for 15 minutes before ladling into sterilised jars. The jam will keep in a cool, dark place for at least six months. Refrigerate jars once opened.