Heat oven to 400?F. Spray bottoms only of mini muffin pan cups with cooking spray.
For topping, combine sugar and cinnamon in small bowl; mix well and set aside.
For muffins, combine flour, oats, sugar and baking powder in large bowl; mix well. In small bowl, combine milk, egg, margarine and vanilla; blend well. Add to dry ingredients all at once; stir just until dry ingredients are moistened. (Do not overmix.)
Fill muffin cups two-thirds full. Sprinkle topping evenly over tops of muffins.
Bake 12 to 14 minutes or until light golden brown. Cool muffins in pan on wire rack 5 minutes; remove from pan. Serve warm.