Blueberry Banana Muffins-this is a staple for us

1 cup all-purpose flour
2 cup whole wheat flour
1 1/4 cup white sugar
1/2 cup ground flax
1 cup quick cooking oats
2 teaspoons baking powder
2 teaspoons baking soda
1/2 teaspoon salt
2 cup blueberries
3/4 cup chopped walnuts, optional
2 bananas, mashed
2 cup buttermilk
2 egg
2 tablespoons vegetable oil
2 teaspoons vanilla extract

DIRECTIONS
1. Preheat the oven to 350 degrees F (175 degrees C). Grease 2- 12 cup muffin pans, or line with paper muffin cups.
2. In a large bowl, stir together the all-purpose flour, whole wheat flour, sugar, ground flax, quick-cooking oats, baking powder, baking soda and salt.
3. Gently stir in the blueberries and walnuts. In a separate bowl, mix together the mashed banana, buttermilk, egg, oil and vanilla.
4. Pour the wet ingredients into the dry, and mix just until blended. Spoon into muffin cups, filling all the way to the top.
Bake for 15 to 18 minutes in the preheated oven, or until the tops of the muffins spring back when lightly touched.