Ingredients:

  • 6 cups fresh blackberries (900g)
  • 4 cups granulated sugar (800g)
  • 2 tbsp fresh lemon juice (30ml)
  • 1 tsp butter (5g)

Instructions:

  1. Place the washed blackberries in a heavy-bottomed pot and use a potato masher to crush about half of the berries, leaving some whole for texture.
  2. Stir in the sugar, lemon juice, and butter. Heat over medium-low, stirring constantly until the sugar has completely dissolved and the mixture is glossy.
  3. Increase heat to medium-high and bring the mixture to a full, rolling boil, stirring frequently to prevent sticking.
  4. Continue boiling until the jam reaches 220°F (104°C) on a candy thermometer.
  5. Verify the set using the Plate Test: drop a spoonful of hot jam onto a chilled plate; it should set within 30 seconds.