1. Lightly grease and flour a 10 inch tube pan.
Preheat oven to 350º. Sift 3 c. flour with baking powder, soda and salt. Set aside.
2. In small bowl, combine brown sugar with 1 T. flour and cinnamon. Mix well.
3. In large bowl with electric mixer, at medium speed, beat butter with granulated sugar and vanilla until fluffy. Add eggs one at a time, beating after each addition.
4. At low speed, beat in flour mixture alternately with sour cream, beating until combined.
5. Turn 1/3 of batter into pan, spreading evenly. Sprinkle with half the blueberries and half the brown sugar mixture. Repeat layering of remaining batter, blueberries and brown sugar mixture.
Bake 60 min. or until cake tester comes out clean.
6. Cool in pan on wire rack 20 min.
7. Gently remove from pan. Mix powdered sugar and milk until smooth; drizzle over cake.