Preheat oven to 400°F. Grease twelve 1/2-cup muffin cups. Mix first 5 ingredients in large bowl. Whisk buttermilk, oil and egg in small bowl. Add to dry ingredients and stir just until blended. - stand 15 minutes at room temperature. (Batter can be prepared 2 days ahead; refrigerate.) Mix remaining ingredients in small bowl. Spoon 2 tablespoons batter into bottom of each prepared cup. Cover evenly with apple mixture. Spoon remaining batter over. Bake until tester inserted in centers comes out clean, about 23 minutes. Cool muffins in cups on rack 3 minutes. (Can be prepared 1 month ahead. Cool completely. Wrap each muffin in foil and freeze. Rewarm in 350°F oven before serving.) Serve muffins hot. bake 03