bowl, cream half cup of the butter with electric mixer 1 minute, until blended. Gradually add sugar and beat until light and fluffy, about 2minutes. Beat in eggs, sour cream and vanilla 2 minutes more.
In medium bowl, whisk together 2 cups of flour, baking powder, baking soda, and salt. Stir into creamed mixture, mixing just enough to blend in dry ingredients. Spoon half of batter into a greased 9 or 25 cm tube pan or a 9 x 13 pan, spreading evenly. In small mixing bowl, mix brown sugar, cinnamon, remaining half cup flour and remaining 2 T. butter until crumbly. Sprinkle half of this topping over batter in pan. Sprinkle blueberries evenly over topping. Drop Remaining batter by spoonfuls over blueberries and spread evenly with rubber spatula to cover blueberries. Sprinkle with remaining cinnamon topping. Bake at 350 degrees 1 hour. Remove from oven and let cool in pan on wire rack 5 minutes; place cookie sheet over top of coffee cake, invert cake and remove from pan, then turn cake right side up again and place on wire rack to complete cooling. Note: Cake Freezes well.