Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan, tapping out the excess flour.

In a large mixing bowl, beat the softened butter and granulated sugar until light and fluffy, about 3–5 minutes.

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

In another bowl, whisk together the flour, baking powder, baking soda, and salt until evenly combined.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.

Pour the batter into the prepared pan and smooth the top with a spatula.

Bake for 30–35 minutes until a toothpick inserted in the center comes out clean.

Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Serve plain, dusted with powdered sugar, or topped with a simple glaze or fresh fruit.