Preheat oven to 375 degrees Fahrenheit and prepare an 8×8 inch square pan by lining it with parchment paper and spraying it with cooking spray.
Make the crust by whisking together the 1 ½ cups all-purpose flour, ½ cup light brown sugar, ½ teaspoon baking soda, ½ teaspoon baking powder, and ¼ teaspoon salt. Add in the ½ cup butter, The dough will be crumbly so make sure all the butter is incorporated.
Reserve 3/4 cup of the crust and press the remaining crust into the bottom of the prepared baking pan.
Mix the 2 cups fresh blueberries, ¾ cup granulated sugar, 2 teaspoons cornstarch, and 1 tablespoon lemon juice in a small bowl until combined and set aside.
For the sour cream filling, mix together in a large bowl the ½ cup sour cream, ¼ cup granulated sugar, 1 tablespoon all-purpose flour, 1 egg, and ½ teaspoon vanilla extract. Pour the filling over the crust in the pan
Spoon the fresh blueberry mixture evenly over the sour cream.
Sprinkle the reserved ¾ cup crust over the top and bake for 25-28 minutes or until golden brown. Cool completely before cutting and serving.