1Heat oven to 400°F. Place paper baking cup in each of 6 regular-size muffin cups or spray bottoms only of muffin cups with cooking spray.
2Place 1/4 cup cereal in resealable food-storage plastic bag; seal bag. Using rolling pin, slightly crush cereal; pour into small bowl. Stir in flour, brown sugar and butter until crumbly. Set aside.
3Place 1 1/2 cups cereal in resealable food-storage plastic bag; seal bag. Using rolling pin, slightly crush cereal; set aside. In medium bowl, place muffin mix, milk and oil. Stir in egg just until moistened (batter will be lumpy). Stir in crushed cereal. Divide batter evenly among muffin cups. Sprinkle streusel evenly over tops.
4Bake 15 to 20 minutes or until muffins are golden brown and tops spring back when touched lightly. Immediately remove from muffin cups. Cool 5 minutes before serving.