Preheat the oven to 400°F (200°C). Line the muffin tin with paper liners.
Melt butter in a small pan. Let it cool slightly until you need it.½ cup unsalted butter
Dry ingredients: Whisk flour, baking powder, baking soda, sugar, and a pinch of salt in a large bowl with an egg whisk.2 ⅔ cups all-purpose flour + 2 teaspoons baking powder + ½ teaspoon baking soda + 1 cup sugar + pinch of salt
Wet ingredients: Whisk buttermilk, eggs, vanilla extract, vinegar, and melted butter in a medium bowl.1 ¼ cup buttermilk + 2 eggs + 1 tablespoon vanilla extract + 1 teaspoon vinegar + butter
Combine: Pour the wet ingredients over the flour mixture. Stir gently and shortly until just combined. Don’t over-stir. If you want to add chocolate, berries, or nuts, carefully fold them in now (Note 5).
Bake: Scoop the batter into the cups. Bake for about 20 minutes or until a toothpick inserted in the middle of a muffin comes out clean.
Rest for 5 minutes in the pan. Remove and let cool on a wire rack. If desired, sprinkle with icing sugar before serving.
Notes
Measurements: A digital kitchen scale will give you the most precise measure, ensuring the best bake possible.
Flour: I prefer cake flour when baking muffins; it makes them more tender. But plain/all-purpose flour is fine as well.
Sugar: Fine sugar would be perfect, but granulated sugar is ok too.
Vinegar: Apple cider vinegar, red or white wine vinegar.
Additions: You can fold in between ½ and 1 cup of chocolate chips (semi-sweet, white, chocolate chunks, or chopped chocolate), nuts (walnuts, pecans, almonds, etc.), or berries of choice.