Preheat your oven to 350°F (175°C).
Grease and flour two 9-inch round cake pans.
In a large mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Mix in the buttermilk and pumpkin spice, combining well.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing gently.
Fold in the chopped nuts if using.
Divide the batter between the prepared pans and smooth the tops.
Bake in the preheated oven for 25-30 minutes, or until a toothpick comes out clean.
Allow cakes to cool in the pans for 10 minutes before transferring to wire racks.
Frost and decorate as desired once fully cooled.
