Preheat the oven to 350°F. With butter and flour, grease each mini bundt pan well (this is the pan I used). You can also use a 10-cup Bundt pan.
In a medium bowl, whisk together flour, salt, baking powder, and baking soda. In a liquid measuring cup, whisk together the buttermilk, vanilla, and lemon juice.
In a large bowl or stand mixer bowl, combine the butter, sugar, and lemon zest with an electric mixer on medium speed for about 4 minutes or until light and fluffy. Beat in the eggs and egg yolk one at a time until combined.
Beat in 1/3 of the flour mixture followed by half of the buttermilk. Repeat with half of the remaining flour and remaining buttermilk. Finish by folding in the remaining flour until just incorporated. Fold in the blueberries.
Fill each mini bundt pan about 2/3 of the way full. You may need to bake in two batches depending on your pan.
Bake for about 25-30 minutes, or until a wooden skewer inserted into the center comes out clean. If your using a regular bundt pan, bake for 45-50 minutes. Let cakes cool for 20 minutes in the pan and then flip onto a wire rack to cool completely.
For the glaze
Combine all of the ingredients in a blender and puree until blueberries are blended and glaze is smooth. Add more powdered sugar if you'd like a thicker glaze. Pour over cooled cakes.