In a medium bowl, combine all ingredients. Use your hands, two knives or a pastry blender mix until mixture is crumbly. Set aside.
Grease baking dish using the paper you removed from butter.
In a large bowl add flour, baking soda, baking powder and salt. Mix using a whisk to lighten flour. Set aside.
Add butter, sugar and vanilla in the electric mixer bowl. Use the paddle attachment and cream until light and fluffy. Takes about 5 minutes.
Add egg one at a time and let it mix in before adding the next one. Now alternate adding flour and sour cream a spoonful at a time. Batter should be light and fluffy.
Fold in 2 cups of blueberries. They can be dusted with a tablespoon of flour so they don’t sink to the bottom. Spread mixture in baking dish.
Add remaining blueberries to crumb topping. Mix gently and sprinkle over cake.
Bake at 350°F (180°C ) for one hour.
Enjoy!