1. Preheat oven 350 degrees and spray a 9×13-inch baking pan with non stick cooking spray.
2. In a medium bowl, whisk together the flour, sugar, baking powder, and salt.
3. Add the oil, milk, and eggs.
4. Mix with an electric mixer for 3 minutes.
5. Pour the batter into the prepared pan, then evenly sprinkle the blueberries on top.
6. In a small bowl, combine the 3 tablespoons of sugar and cinnamon, then sprinkle over the blueberries.
7. Bake 50 minutes or until a toothpick inserted into the center comes out clean.