Preheat oven to 350F. Grease and flour three 7 inch removable bottom cake pans, then line with parchment.
In a medium bowl, whisk flour, baking powder, and salt until well combined.
Using a stand mixer fitted with the paddle attachment, beat butter until smooth.
Add sugar and beat on med-high until pale and fluffy (about 3-4 mins).
Reduce speed and add eggs, one at a time, fully incorporating after each addition.
Add vanilla extract and lemon zest and continue beating.
Alternate adding flour mixture and buttermilk. Begin and end with flour (3 additions of flour and 2 of buttermilk). Fully incorporate after each without overmixing.
Mix blueberries with flour and toss gently to avoid breaking the fruit.
Using a spatula, fold in the blueberries into the batter, making sure you don't break the fruit.
Spread batter evenly into prepared pans and smooth the top with a spatula.
Wrap a wet towel (100% cotton towel) around the cake pans before placing in the oven.
Bake for 30-35 mins or until a toothpick inserted into the center comes out mostly clean.
Place cakes on wire rack to cool for 10 mins then turn out onto wire rack to cool completely.