Preheat the oven to 350 degrees F. Line an 8x8-inch baking pan with parchment paper.
In a medium bowl, cream the butter and sugar together until light and fluffy. Beat in the vanilla extract.
In a separate bowl, whisk together the flour and salt. Slowly add the flour mixture to the butter mixture, stirring until the dough comes together.
Press the dough into the prepared baking pan and bake for 20 minutes.
While the shortbread is baking, combine the blackberries, brown sugar, cornstarch, and cinnamon in a medium bowl. Stir until the blackberries are evenly coated.
Remove the shortbread from the oven and spread the blackberry mixture over the top. Return to the oven and bake for an additional 15 minutes.
Remove from the oven and let cool before slicing into bars.
Interesting Facts
Shortbread is a type of cookie that originated in Scotland.
Blackberries are a type of berry that is native to North America.
The combination of sweet and tart flavors is a classic in desserts.