In a small bowl add the streusel ingredients. Mix with a fork until combined. I've found if the butter is slightly melted, this step goes better.
In a larger bowl add the cake mix, cream cheese, eggs, water and oil. Mix together with a hand mixer until smooth, don't over mix though.
Spray a 9x13 pan with non-stick spray. Add half of the batter to the pan, spread out evenly. Sprinkle over the blueberries. Add remaining batter and spread on top of blueberries.
Sprinkle over the struesel.
Place in the oven on the center rack. Bake for 45 minutes or until a toothpick comes out clean when inserted in the middle of the cake. Place on a cooling rack. Serve warm or room temperature. Enjoy!
The best way to store this cake is to let it cool completely, then wrap in plastic wrap and move to the fridge. Let sit overnight or up 24 hours before serving. The flavor actually increases the longer you let it rest!Can I use a different kind of fruit?Sure! Make it with raspberries, strawberries, or cherries instead - even peaches would work well with this recipe.