Preheat oven to 350℉/177℃.
Spray 8-inch x 12-inch pan with baking spray. Set aside.
Rinse and drain blueberries. Set aside.
In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt. Set aside.
In a medium bowl, combine milk, eggs, and vegetable oil.
Stir wet ingredients into dry ingredients.
Fold in blueberries.
Pour into prepared pan.
Top with streusel.
Bake for 35 minutes, or until cake tests done.