Heat oven to 350. In larger mix bowl, combine sugar, buttermilk, butter, eggs and vanilla. Beat at medium speed, scraping bowl often until creamy (1-2 min). Add flour, baking soda, and salt. Beat at low speed until moistened (1-2 min). By hand, stir in blueberries. Spoon into paper lined muffin cups. Bake for 25-30 min. or until toothpick inserted into the center comes out clean. Remove from pan, cool and sprinkle with powdered sugar.