In large bowl, combine flour, brown sugar, sugar, baking powder, baking soda and salt; mix well. Add buttermilk, oil, vanilla and eggs; stir just until dry ingredients are moistened. Batter can be baked immediately or stored in tightly covered container in refrigerator for up to 5 days.
When ready to bake, heat oven to 375°F. Grease bottoms only of desired number of muffin cups or line with paper baking cups. Stir batter; fill greased muffin cups 2/3 full.
Bake at 375°F. for 20 to 25 minutes or until toothpick inserted in center comes out clean. Immediately remove from pan. Serve warm.