Preheat oven to 350°F and line muffin pans with paper liners, sixteen liners in all.

Whisk together dry ingredients in a large bowl: flours, sugar, baking powder, baking soda, cinnamon, and salt. Set aside.

In a blender, place oil, milk, and spinach. Blend on high for about 30 seconds or until completely puréed. Add banana and vanilla; blend on low just to mix.

Pour puréed mixture into dry mixture and fold together until completely combined.

Fill muffin cups about ⅔ full and bake 18-20 minutes or until a toothpick inserted into the center comes out clean.

If serving to children:
Call them Popeye's cupcakes
For the holiday season, put a little red frosting or decor on it, or affix a holiday baking decoration.
Put a strip of colour-appropriate frosting and a couple chocolate chips on it to make it a Ninja Turtle cupcake.