Preheat your oven to 350°F (175°C). Line a muffin tin with cupcake liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, using an electric mixer.

Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk. Begin and end with the dry ingredients, mixing just until combined after each addition.

Fill the cupcake liners about ¾ full with the batter.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.

Remove the cupcakes from the oven and let them cool in the muffin tin for about 5 minutes. Then, transfer them to a wire rack to cool completely before frosting.

In a large mixing bowl, beat the softened butter until creamy and smooth.

Gradually add the powdered sugar, about 1 cup at a time, mixing well after each addition.

Add the milk or heavy cream, one tablespoon at a time, until the desired consistency is reached. Stir in the vanilla extract and mix until well combined.

Once the cupcakes have cooled completely, frost them with the vanilla buttercream frosting using a piping bag or spatula.

Optional: Decorate the cupcakes with sprinkles, edible pearls, or any desired toppings.