01 - Preheat oven to 400°F. Grease a 24-cup mini muffin tin with melted butter or nonstick spray.
02 - In a medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt until well blended.
03 - In another bowl, whisk together buttermilk, egg, melted butter, and vanilla extract until smooth and combined.
04 - Pour wet ingredients into dry ingredients and mix gently until just combined. Do not overmix; a few small lumps are acceptable.
05 - Gently fold in chocolate chips or blueberries if desired.
06 - Spoon batter evenly into the prepared mini muffin tin, filling each cup about 3/4 full.
07 - Bake for 8-10 minutes until tops are golden brown and a toothpick inserted into the center comes out clean.
08 - Let cool for 2 minutes in the pan, then carefully remove. Serve warm with maple syrup, melted chocolate, or fruit preserves.