Preheat oven to 425°.
In a large bowl sift flour. Re-sift flour with baking powder and salt. In seperate bowl cream sugar and softened butter. Add milk and egg til smooth. Add oats to flour mixture. Add egg and milk. Mix just until moist. Fill greased muffin tins (or use paper liners) 2/3 full. Bake 15 - 20 minutes.
Topping
1/3 C brown sugar
1 T flour
2 t cinnamon
1 T butter
Mix sugar, flour and cinnamon. Add butter. Sprinkle on top of muffins before baking. Bake 15 - 20 minutes.
