Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, cream the softened butter and granulated sugar together until light and fluffy, about 3-5 minutes.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk, beginning and ending with the flour mixture. Mix until just combined.
Fold in the chopped pecans gently.
Divide the batter evenly between the prepared cake pans.
Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then transfer to wire racks to cool completely.
Serve with whipped cream or cream cheese frosting if desired.