Preheat your oven to 350°F (180°C) and line a baking sheet with parchment paper.

If using frozen blackberries, let them thaw and puree about ¾ cup until smooth, yielding ½ cup blackberry puree.

In a mixing bowl, cream together ½ cup softened butter and 1 cup granulated sugar until light and fluffy. Add the blackberry puree and 1 teaspoon vanilla extract, mixing well.

In a separate bowl, whisk together 1½ cups flour, 1 teaspoon baking soda, and ¼ teaspoon salt. Gradually incorporate this mixture into the wet ingredients.

Fold in ½ cup chocolate chips gently.

Chill the dough for at least 30 minutes.

Scoop out dough portions, roll into balls, and flatten slightly on the prepared baking sheet. Bake for 8-10 minutes until edges are set.

Let cookies cool on the tray for 5 minutes before transferring to a wire rack.