In a blender, blend oats until the consistency is similar to flour.
Combine all dry ingredients in the blender and blend until mixed.
Add all other ingredients except walnuts in the blender and blend until smooth.
Add walnuts and mix with a mixing spoon.
Pour batter into a muffin tin lined with muffin liners. Top with additional walnuts if desired.
Bake at 350 degrees for 17-20 min (check that middle is cooked with a toothpick and bake longer if necessary).
Remove muffins from muffin tin and let them cool on a cooling rack before serving.