Preheat oven to 375°F/190°C. Line an 8x8 square pan with parchment paper and spray with cooking spray.
In a medium bowl, whisk together the flour, brown sugar, baking soda, baking powder, and salt for the crust. Stir in the melted butter until incorporated and the dough is crumbly.
Reserve 3/4 cup of crust dough and press the remaining dough evenly into the bottom of the prepared baking pan.
In a small bowl, gently combine the blueberries, sugar, cornstarch, and lemon juice. Set aside.
In a large bowl, mix together the sour cream, sugar, flour, egg, and vanilla for the filling. Pour the filling over the crust in the pan.
Spoon the blueberry mixture evenly over the sour cream filling.
Sprinkle the reserved 3/4 cup of crust dough over the top and bake for 25-28 minutes or until golden brown. Cool completely and cut into squares before serving. Store in the refrigerator for up to 3 days.