1In a bowl, cream 1/2 cup of the butter with electric mixer 1 minute, until blended.
2Gradually add sugar and beat until light and fluffy, about 2 minutes.
3Beat in eggs, sour cream and vanilla 2 minutes more.
4In medium bowl, whisk together 2 cups of flour, baking powder, baking soda and salt.
5Stir into creamed mixture, mixing just enough to blend in dry ingredients.
6Spoon half of batter into a greased 9 or 10 inch tube pan or a 9 x 13 pan, spreading evenly. In small mixing bowl, mix brown sugar, cinnamon, remaining 1/2 cup flour and remaining 2 tablespoons butter until crumbly. Sprinkle 1/2 of this topping over batter in pan.
7Sprinkle blueberries evenly over topping. Drop remaining batter by spoonfuls over blueberries and spread evenly with rubber spatula to cover blueberries.
8Sprinkle with remaining cinnamon topping.
9Bake 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. Cake freezes well.