Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar using an electric mixer until the mixture is light and fluffy, about 2-3 minutes.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract until combined.
In a separate bowl, whisk together the sifted flour and chocolate chips. Gradually add this dry mixture to the wet ingredients, mixing on low speed just until incorporated.
Gently fold in the fresh blackberries, being careful not to crush them too much to maintain their shape and juiciness.
In a separate bowl, prepare the crumble topping by combining the flour, granulated sugar, brown sugar, oats, and cold butter pieces. Use your fingers or a pastry cutter to blend until the mixture resembles coarse crumbs.
Drop rounded spoonfuls of cookie dough onto the prepared baking sheet, spacing them about 2 inches apart.
Sprinkle the crumble mixture evenly over each cookie dough mound for a crunchy topping.
Bake in the preheated oven for 12-15 minutes, or until the edges are golden brown and the centers look set but still slightly soft.
Remove the cookies from the oven and allow them to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
Enjoy these cookies once they are completely cooled—deliciously crispy on the edges with gooey centers, dotted with juicy blackberries and chocolate chips.
