Heat oven to 375°F Place paper baking cup in each of 12 regular-size muffin cups. Place cereal in resealable food-storage plastic bag; seal bag and crush with rolling pin or meat mallet (or crush in food processor).
In medium bowl, mix cereal and buttermilk; let stand 5 minutes. Stir in oil and egg. Stir in remaining ingredients except chocolate chips. Stir in chocolate chips. Divide batter evenly among muffin cups.
Bake 15 to 20 minutes or until toothpick inserted in center comes out clean. Immediately remove from pan. Serve warm.