When looking for a perfect blackberry lemon filling to add to cookies and cheesecakes, this is a homemade quick and easy filling. The filling can be made the day before and refrigerated overnight.
Wash and clean the blackberries. Add them to a saucepan along with the sugar and the lemon zest. Bring to a boil and continue to stir and smash the blackberries for 5 to 10 minutes. They soften as you cook them.
Mix the lemon juice and cornstarch in a small bowl and add it to the blackberry filling. Turn the heat down to a medium-low so that it is gently boiling. Continue for 5-7 minutes until it thickens slightly. Move the pan off the heat to cool slightly. Pour into a glass jar and let it cool for half an hour. At a lid and refrigerate overnight.