Preheat oven to 350°F. Grease and flour a 10-cup bundt pan. Set aside.
In a medium bowl, combine the flour, baking powder, salt, and baking soda. Set aside.
2¼ cups all-purpose flour, 2½ teaspoons baking powder, 1 teaspoon kosher salt, ½ teaspoon baking soda
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together on medium-high speed for 1 minute. Add in the eggs and continue to beat for another minute. Add in the sour cream and beat until a smooth mixture has formed.
½ cup unsalted butter, 1¼ cups granulated sugar, 3 large eggs, 1 cup sour cream
Add the flour mixture into the wet mixture and stir just until the flour is incorporated. Fold in the blueberries.
2 cups blueberries
Pour the batter into the bundt pan. Place into the preheated oven and bake for 70-85 minutes, or until a toothpick comes out clean or with moist crumbs. Remove from the oven and set on a cooling rack to cool for 20 minutes.
Once partially cooled, invert the cake onto a plate or cake stand and let cool completely.
While the cake is cooling, make the glaze by whisking the glaze ingredients together in a medium bowl until smooth. If the glaze is too thick, add more milk, 1 teaspoon at a time, until the desired consistency is reached.
2 cups powdered sugar, ¼ cup milk, 1 teaspoon pure vanilla extract
Once the cake is cooled, drizzle glaze over top. Garnish with fresh blueberries if so desired. Slice and serve!