Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

In another bowl, combine the flour, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the butter mixture, alternating with buttermilk and vanilla extract. Mix until just combined.

Fold in the toasted pecans.

Pour the batter into the prepared cake pan and smooth the top.

Bake in the preheated oven for 35-40 minutes or until a toothpick inserted into the center comes out clean.

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