Preheat your oven to 325F. Grease and flour your 9x5 inch loaf pan. Alternatively, you can line the pan with parchment paper.
Add the butter, sour cream, cream cheese, and vanilla extract to the bowl of a stand mixer and beat on medium-high using the paddle attachment until well-combined, smooth, and creamy.
Scrape the bottom and sides of the bowl and then add in the eggs. Beat well on medium-high speed until fully combined.
Mix together the dry ingredients into a separate bowl. Add the blueberries and a tablespoon of flour together into a small bowl.
Slowly add the dry ingredients to your wet ingredients and mix on low speed just until there are no streaks of flour.
Scrape the bottom and sides of the bowl once more and them gently fold in the blueberries.
Pour the batter into your prepared pan and bake until golden brown. About 40 - 45 minutes, or until the top is golden brown or a toothpick inserted into the center of the cake comes out with a few moist crumbs clinging to it.
Make the icing while the cake cools. Mix everything together in a small bowl until smooth
Let the cake cool on a wire rack before topping with your icing and finished with fresh blueberries, if desires