Preheat the oven to 400°F (200°C).
Grease a 24-cup mini muffin pan with butter or nonstick spray.
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
Create a well in the center of the dry ingredients.
Add the milk, melted butter, egg, vanilla extract, and lemon zest.
Stir gently until a smooth batter forms and no large lumps remain.
Fill each mini muffin cup about three-quarters full.
Place approximately 3 blueberries into each cup, gently pressing them slightly into the batter.
Bake for 12–14 minutes or until the tops are lightly golden brown.
Remove from the oven and allow the bites to cool for 5 minutes.