Preheat the oven to 400 degrees
In a large bowl, whisk together the wet ingredients (egg, buttermilk, melted butter, and vanilla extract).
In a smaller bowl, mix together the dry ingredients (flour, sugar, baking powder, baking soda, salt).
Add in the dry ingredients to the wet ingredients. Stir with a rubber spatula until the dry ingredients are completely mixed in (only about 10 seconds). Leave the lumps!
Gently fold in the blueberries, turning only enough for them to evenly be placed in the batter. Again, be gentle with the batter. Do not over mix.
Line a muffin tin with parchment paper or muffin liners.
Scoop in 2 tablespoons of batter into each muffin liner (about 10 muffins)
Bake for 25 minutes