Preheat oven to 375º F /190º C and grease or line a muffin tin.
To make oat flour, put 2 cups of old-fashioned oats in your blender and blend until the oats achieve the texture of flour. Skip this step if you already have oat flour.
In a mixing bowl, add the oat flour and the rest of the dry ingredients (ground flaxseed, baking powder, baking soda, salt, cinnamon, and sugar).
Mix until well combined.
Add almond milk to the blender, followed by 2 cups of spinach.
Blend together until completely smooth.
Add bananas and coconut oil and blend until smooth.
Then add vanilla and eggs and blend until well combined.
Pour the blended mixture into the bowl with dry ingredients and stir to combine.
Fill each well in your muffin tin with ¼ cup of batter.
Bake for 20-25 minutes. Or until a toothpick comes out clean and the top springs back when touched.
Let the muffins cool for 10 minutes before serving.