In a large bowl combine the dry ingredients whole wheat flour, baking soda, salt and cacao powder mix and set aside, 

In another bowl mix melted butter, maple syrup, eggs and mashed bananas, mix well. You want to make sure the spinach is almost liquid when you mix it with the wet ingredients. To make this happen, grab any high power blender and add the milk and spinach and blend. Next add the blended spinach to the wet ingredients. Next add the dry ingredients to the bowl of wet ingredients. At this time you can even add mini chocolate chips. Scoop into muffin tins and bake for 15-18 minutes at 350 degrees. 

Should make around 15 muffins.