Preheat the oven to 400 degrees F (200 degrees C). Spray an 8x8-inch baking pan with cooking spray.
Toss blueberries and 1/2 cup of flour in a small bowl until blueberries are coated. Set aside.
Beat together sugar and oil with an electric mixer in a large bowl. Add milk, egg, and vanilla extract. Mix remaining 1 cup flour, baking powder, and salt in a small bowl. Add flour mixture to sugar mixture; mix until just combined. fold in blueberry mixture. Pour batter into the prepared baking pan.
Mix together brown sugar, 1/3 cup flour, and cinnamon in a bowl. Cut in butter until topping mixture is crumbly. Sprinkle on top of the cake batter.
Bake in the preheated oven until a toothpick inserted in the center comes out clean, about 30 minutes. Remove from oven and allow to cool before serving.