Banana Bran Muffins

Banana Bran Muffins
1 cup all purpose flour
1 tsp. baking powder
½ tsp. baking soda
¼ tsp. salt
1 cup All Bran cereal
1 cup mashed, ripe banana
2 eggs
1 tsp. vanilla extract
¼ cup butter, softened
½ cup sugar
½ cup walnuts (optional - I didn't use this time)

Preheat oven to 350 degrees.  Stir together the flour, baking powder, baking soda, and salt.  Set aside.  In a separate bowl mix together the bran cereal, bananas, eggs, and vanilla.  Let stand about 5 minutes or until softened.  In a large mixing bowl, beat together the butter and sugar until combined.  Add flour alternately with the cereal mixture.  Mix well after each addition.  Stir in walnuts if desired.    Pour into prepared muffin pan and bake for 20 minutes or until cooked through.