Grease and flour a bundt or tube pan; set aside. Preheat the oven to 350°F.
Cream sugar and butter together in a large bowl until light and fluffy. Add in the eggs one at a time, mixing until yolk disappears, then the vanilla.
In a separate bowl, whisk together flour, baking powder, baking soda, and salt. Add to cream mixture, alternating with the sour cream, until well combined.
In a small bowl combine brown sugar, flour, and cinnamon; set aside.
Pour a third of the batter into prepared baking pan, spreading evenly.
Sprinkle half of the brown sugar mixture over the batter in the pan. Place half of the blueberries on top. Repeat layers then top with the remaining batter.
Bake until toothpick inserted in the center comes out clean, about 55-65 minutes. Allow cake to cool in the pan, set on a wire baking rack for 10 minutes. Remove from pan and let cool completely on wire baking rack.
Meanwhile, prepare the glaze. In a medium mixing bowl, whisk the powdered sugar and 2 tablespoons of milk together until smooth. Add more milk as necessary to obtain a pouring consistency.
Drizzle glaze over cooled coffee cake. Garnish with fresh blueberries.
Notes
Keep leftovers in an airtight container for 5 days at room temperature or in the refrigerator.