Begin by preheating your oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper.

In your stand mixer, combine softened unsalted butter with granulated sugar and vanilla extract. Beat on medium speed until light and fluffy, about 2-3 minutes.

Gradually add in the all-purpose flour and salt to the creamed mixture, mixing on low speed until a crumbly mixture forms.

Press about two-thirds of the crumb mixture firmly into the bottom of the prepared baking pan.

Evenly distribute the fresh blackberries over the pressed crust.

Sprinkle the remaining crumb mixture evenly over the layer of blackberries.

Place the pan in your preheated oven and bake for 35-40 minutes, or until the top is golden brown and the edges are bubbling.

Once baked, remove the pan from the oven and allow the bars to cool completely in the pan.