Preheat oven to 375 degrees F and line a muffin tray with paper liners or spray with nonstick cooking spray.
In a small bowl mix together the streusel topping until size of coarse crumbs.
In a large mixing bowl whisk together the cake mix, flour, and baking powder.
In another bowl whisk together the oil, milk, and eggs until well blended.
Make a well in the center of the dry mix and add in the egg mixture.
Whisk until well combined.
Fold in the blueberries
Scoop the batter into the prepared muffin tray.
Fill each one ⅔s of the way full. Sprinkle tops with streusel mixture.
Bake for about 15-20 minutes until tops are golden and a toothpick can be inserted and come out clean.
Let cool for 5 minutes in the baking tray and then transfer to a wire rack to finish cooling completely.