Ingredients

• 4 cups blackberries
• 1 cup white sugar
• 2 tablespoons cornstarch
• 1/4 teaspoon ground cinnamon
• 1/4 teaspoon ground allspice
• 1/2 teaspoon lemon juice

Instructions

1. Mash blackberries in a saucepan with a potato masher. Stir in sugar until juices form; place about 1 tablespoon blackberry juice in a small bowl and stir in cornstarch. Pour cornstarch mixture into saucepan.
2. Bring berries to a boil, stirring often, until jam is thickened, about 15 minutes. Stir in cinnamon and allspice. Remove from heat and allow to cool. Transfer jam to a bowl, cover, and refrigerate until chilled. Stir in lemon juice.