In a large bowl combine the first five ingredients.
In another bowl combine egg, sour cream, applesauce, oil, and vanilla. Stir into dry ingredients just until moistened. Fold in blueberries. Pour into 9 in square pan coated with cooking spray.
For topping in a bowl combine the brown sugar, oats, and cinnamon; cut in butter until mixture resembles coarse crumbs. Sprinkle over the batter.
Bake at 350 for 40-45 mins, until toothpick comes out clean.