01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup.
02 - In a large mixing bowl, whisk together flour, sugar, baking powder, baking soda, and salt until fully combined.
03 - In a separate bowl, beat eggs thoroughly. Whisk in milk, oil or melted butter, and vanilla extract until smooth.
04 - Make a well in the center of the dry ingredients. Pour in the wet mixture and gently fold together until just combined, avoiding overmixing.
05 - Fold in chosen add-ins such as berries, chocolate chips, or nuts if using.
06 - Divide batter evenly among the muffin tin cups, filling each about three-quarters full.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before serving.