Aunt Norma's Rhubarb Muffins

Details

Ingredients

• 2 ½ cups flour
• 1 teaspoon baking soda
• 1 teaspoon baking powder
• ½ teaspoon salt
• 1 ¼ cups brown sugar
• ½ cup vegetable oil
• 1 egg
• 1 teaspoon vanilla extract
• 1 cup buttermilk
• 1 ½ cups diced rhubarb
• ½ cup chopped walnuts
• 1 tablespoon melted butter
• ⅓ cup white sugar
• 1 teaspoon ground cinnamon