1. Preheat oven to 350 degrees and line a 9x9 square pan with foil or parchment paper. Spray the foil with cooking spray and set aside.

2. For the streusel topping: combine all streusel ingredients (1 cup flour, 3/4 cup sugar, 6 tbsp unsalted butter (melted & cooled) in a small bowl and stir until crumbly. Set aside until ready to use.

3. For the cake: whisk together 1 1/2 cups all purpose flour, 1 tsp baking soda, 1 tsp baking powder and 1/4 tsp salt until well mixed. In a separate bowl, whisk together the oil, cream cheese and 1 cup of sugar until smooth, then add the eggs, yogurt and vanilla and whisk until smooth.

4. Pour wet mixture into bowl with flour and whisk until smooth. Pour cake batter into the prepared pan, then sprinkle with blueberries.

5. Sprinkle the streusel over the top of the berries evenly, pressing it gently into the top of the cake batter.

6. Bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean. Let cool in pan completely before removing and cutting into squares.

7. Optional: whisk together ½ cup powdered sugar and 2 tbsp milk to create a glaze and drizzle over cooled cake.