Grease & flour bottom and side of (tube) cake pan.
In small bowl, mix all Blackberry Filling ngredients; set aside.
in medium bowl, mix flour, baking powder and baking soda; set aside.
In large bowl, beat granulated sugar, butter, vanilla and eggs with electric mixer on medium speed 2 minutes, scraping bowl occasionally.
Beat in flour mixture alternately with sour cream on low speed.
Spread one-third of the batter in pan; sprinkle with half of the filling. Spoon another one-third of the batter by tablespoonfuls over filling; sprinkle with remaining filling. Spoon remaining batter over filling.
Bake 55 to 65 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pan to plate or rack. Cool completely.
In small bowl, stir all Powdered Sugar Glaze ingredients until smooth. Drizzle over cooled coffee cake.