Preheat oven to 375°F. In a large mixing bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Gradually add sugars, about 1/4 cup at a time, beating on medium speed until well combined. Scrape sides of bowl. Add pie spice, baking powder, baking soda, and salt. Beat for 2 minutes more. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Alternately add flour and buttermilk to butter mixture, beating on low speed after each addition just until combined. Fold in 1/2 cup of the nuts. Spread batter in the prepared pans.