In large bowl, beat 1 cup softened butter and the granulated sugar with electric mixer on medium speed, scraping bowl occasionally, about 2 minutes or until fluffy. Beat in eggs, one at a time, just until smooth. Beat in 2 teaspoons vanilla. On low speed, beat in one-third of the flour mixture, then half of the buttermilk, beating well after each addition, just until smooth. Repeat with flour mixture and buttermilk, ending with flour mixture. Scrape side of bowl occasionally. Spread batter evenly in pan. Tap pan on counter 2 or 3 times to eliminate air bubbles from batter.