Preheat the oven to 350°F (175°C).

Grease and flour the 9-inch round cake pans or line with parchment paper.

In a mixing bowl, beat the softened butter and granulated sugar until light and fluffy.

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

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

Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk.

Gently fold in the finely chopped pistachios.

Pour the batter into the prepared pans and smooth the tops.

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

Let the cake layers cool completely before frosting.