1Heat oven to 350. Spray a 8" square baking pan w/ cooking spray. In medium bowl, whisk together sour cream, applesauce, sugar, egg, egg white and Splenda sweetener.
2In lg bowl combine flour, baking powder and baking soda. Cut butter in until crumbly. Make a well in center of mix. Pour in sour cream mix. Add blueberries and gently blend together. Spoon batter into pan.
3To make topping, in bowl, combine 1/3 cup flour, brown sugar, Splenda and melted butter until crumbly. Sprinkle evenly over batter. Bake 25 mins, or until toothpick inserted in center comes out clean.