1. Preheat Oven: Preheat your oven to 350°F (175°C) and grease a loaf pan.
2. Prepare Dry Ingredients: In a medium bowl, whisk together flour, baking powder, and salt. Set aside.
3. Cream Butter and Sugar: In a large mixing bowl, beat softened butter and sugar with a mixer until light and fluffy (about 3-4 minutes).
4. Add Wet Ingredients: Beat in the eggs one at a time, ensuring each is incorporated. Then mix in lemon zest, lemon juice, and vanilla extract.
5. Combine Wet and Dry: Gradually add the dry ingredients to the wet mixture, alternating with buttermilk. Begin and end with the dry mixture.
6. Fold in Blueberries: Toss blueberries with a teaspoon of flour and gently fold them into the batter.
7. Pour and Bake: Pour batter into the greased loaf pan. Smooth the top and bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool the Cake: Let the cake cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely.

Lemon Glaze:

1. In a small bowl, whisk together powdered sugar and milk until smooth.
2. Drizzle over the cooled cake and let it set for 10-15 minutes before slicing.