Preheat the oven to 375 degrees F. Grease a muffin tin with baking spray.
Put 2 cups of old-fashioned oats and 1/4 cup flax seed in your Vitamix and blend until they become the texture of flour. (Alternatively, you could use oat flour and ground flax seed without needing to blend) Transfer to a mixing bowl.
Add the rest of the dry ingredients to the oat and flaxseed mixture--baking powder, baking soda, salt, cinnamon and sugar. Set aside.
Add the almond milk to the blender along with 2 cups of spinach. Blend together until completely smooth.
Put peeled bananas and coconut oil into the spinach mixture and blend until smooth.
Add vanilla and eggs into the blender and blend until just combined.
Pour wet ingredients into to dry mixture and stir to combine.
Fill each muffin tin around 3/4 of the way full with batter. Bake for 20-23 minutes or until toothpick comes out clean.
Let cool and store in a freezer bag. When you'd like one, reheat in the microwave for 30 seconds (make sure it's cool enough before serving to little ones). Enjoy!