Preheat the oven to 375°F.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a stand mixer or with a hand mixer, cream together the room temperature butter and sugar on medium-high speed for 2 minutes until light and fluffy.
Add the egg and extracts, then cream for another 2 minutes until light and fluffy.
Reduce the mixer speed to low and alternate adding the buttermilk and flour mixture, starting and ending with the dry ingredients. Add ⅓ of the dry ingredients, then ½ of the buttermilk, another ⅓ of the dry ingredients, the remaining buttermilk, and finally the last ⅓ of the dry ingredients. Mix until just combined after each addition, being careful not to overmix.
Fold in the blueberries gently.
Spread the batter evenly in a 9×9 inch glass pan lined with parchment paper and sprayed with cooking spray.
Top the batter with the brown sugar crumble.
Bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool before serving.