Preheat oven to 400ºF. Place paper liners in muffin pan.
Mix rhubarb, brown sugar, nuts, and flour lightly. Set aside.
Combine baking mix &sugar.
In another bowl, mix milk an egg and add to dry ingredients.
Mix until moistened. Fold in 3/4 of the rhubarb mixture.
Fill cupcake liners half full.
Sprinkle remaining rhubarb mixture on top of muffins.
Bake for 25 minutes.
Yield: About 12 muffins