Preheat your oven to 375°F (190°C) and grease a muffin tin with non-stick cooking spray or line it with muffin liners.
In a mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt until well combined.
In a separate bowl, mix the buttermilk, egg, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir just until combined. Be careful not to overmix; it’s okay if there are a few lumps.
Gently fold in the fresh blueberries into the batter, ensuring they are evenly distributed.
Spoon the batter into the prepared muffin tin, filling each cup about two-thirds full.
If desired, brush the tops lightly with melted butter for a golden finish.
Bake in the preheated oven for about 15 minutes, or until the fritter bites are puffed and a toothpick inserted in the center comes out clean.
Once done, remove from the oven and let them cool for a few minutes before transferring to a wire rack.
Optionally, dust with powdered sugar before serving.