Rhubarb muffins/cupcakes

In a baking contest I got a blue ribbon for these muffins, hence the name. :) They really are delicious.

Blue Ribbon RHUBARB MUFFINS
1 1/4 c. packed brown sugar   
2 1⁄2 c. unsifted flour
1⁄2 c. salad oil   
1 tsp. Baking powder
1 egg   
1/2 c. chopped nuts, optional
1 tsp. Soda
   2 tsp. Vanilla   
                                                                           1/2 tsp. Salt
                                                                         1 c. buttermilk or sour milk   
                                                                         1 1/2 c. diced rhubarb

Topping   
1 1/2 tsp. Cinnamon
1/3 c. plus 3 T sugar   
1 Tbsp. Melted butter

In mixing bowl, combine brown sugar, salad oil, egg & vanilla; beat until well blended. Stir in buttermilk, rhubarb and nuts. Combine flour, baking powder, soda & salt. Add all at once to rhubarb mixture; stir just until mixed. Fill greased muffin pans 2/3 full. Combine sugar, cinnamon & butter. Sprinkle over muffins; press gently into batter. Bake at 400˚ for 20 minutes. Yield 2 doz.