Preheat your oven to 350°F (175°C) and line a cupcake pan with paper liners.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy, about 3-4 minutes.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk, starting and ending with the flour mixture. Mix until just combined; do not overmix.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.