Pre-heat your oven to 375 (F). Line your muffin tin with paper cups.
Mix together the flour, sugar, baking powder, baking soda, and salt in a large bowl and then set aside.
Whisk together the buttermilk, butter, eggs, lemon zest and vanilla in a smaller bowl. Add this to the dry mixture and give 10 stirs. The batter will be quite thick, you want to just barely get things lightly combined.
Add in the blueberries and fold into the batter with 5 stirs. Stir this just enough to evenly distribute the blueberries throughout the batter.