Add egg and mix well.
Sift flour, baking powder, and salt in a small bowl. Add flour mixture and milk alternately to butter mixture. Add vanilla. Gently stir in strawberries.
Spoon batter into muffin pans.
Combine sugar and cinnamon and sprinkle over muffins.
Bake at 400º for 20-25 minutes.
Makes one dozen muffins.
Fresh Strawberry Muffins