1 1/4 c. brown sugar
1/2 c. oil
1 egg
1 c. buttermilk
2 tsp. vanilla
1 1/2 c. finely diced frozen or fresh rhubarb
1/4 tsp. black walnut flavoring (this is a must)
1 1/2 c. flour
1/2 c. chopped nuts
1 tsp. baking soda
1 tsp. baking powder
1 tsp. salt

Mix all ingredients. Fill 20 muffin tins and top with following mixed: 1/3 cup sugar, 1 teaspoon cinnamon, 1 teaspoon butter, softened and 1 teaspoon flour. Press lightly on top of muffins. Bake at 375 degrees for 20 to 25 minutes.