Heat 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
Place 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
Place 1½ cups cereal in a bag; crush lightly. In a bowl, mix muffin mix, milk, and oil, then stir in egg and crushed cereal. Divide batter into muffin cups and sprinkle streusel evenly over tops before baking
Bake 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
