Prepare a 9x13 baking pan by spraying it with cooking spray. Preheat the oven to 350 degrees Fahrenheit.
In a large bowl, whisk together the yellow cake mix, milk, eggs, vegetable oil. Mix well, but do not overmix.
Lightly coat the blueberries in 2 Tablespoons of flour. Fold the blueberry flour mixture into the rest of the cake mix.
Pour cake mix in the baking pan and spread the batter to the edges of the pan. Set aside.
In a small bowl, mix the sugar, flour, butter, and cinnamon together to form the streusel topping.
Sprinkle the topping evenly over the batter in the baking pan.
Bake in the oven for 30-35 minutes. Check the cake with a toothpick to make sure it is completely cooked before taking it out of the oven.
Let the cake cool before cutting and serving.
Calories: 107kcal | Carbohydrates: 12g | Protein: 1g | Fat: 6g | Saturated Fat: 5g | Trans Fat: 1g | Cholesterol: 28mg | Sodium: 26mg | Potassium: 30mg | Fiber: 1g | Sugar: 9g | Vitamin A: 100IU | Vitamin C: 1mg | Calcium: 15mg | Iron: 1mg