Step 1

Spray a 9x13 baking dish with non-stick spray and set aside. Preheat oven to 350°F.

Step 2

Combine flour and sugar in a mixing bowl. Add in butter cubes and mix quickly, so that butter is incorporated and mixture is crumbly. Remove 3/4 cups of the mixture and set aside.

Step 3

Add in baking powder, salt, vanilla, milk and egg whites. Mix batter thoroughly for 3-4 minutes on medium-high speed.

Step 4

Pour cake batter into prepared pan. Sprinkle with blueberries and reserved crumble mixture.

Step 5

Bake at 350°F for 30-35 minutes, until golden brown.