Preheat the oven to 350°F and line a 12-cup muffin tin with paper liners, then lightly spray the liners with cooking spray.
Blend the oats in a blender until they become a fine flour, 30-45 seconds.
Add the spinach, cottage cheese, bananas, eggs, maple syrup, coconut oil and vanilla. Blend for about 1 minute, until completely smooth and bright green with no visible spinach flecks.
Add the cinnamon, baking powder, baking soda and salt, then pulse 5-6 times just to combine.
Pour the batter into a bowl and stir in most of the mini chocolate chips. Let it rest for 10 minutes so the oats absorb the liquid and the batter thickens.
Divide the batter among the cups and top with the remaining chocolate chips.
Bake for 18-22 minutes, until the tops spring back when lightly pressed and a toothpick comes out clean. Avoid overbaking to keep the color vibrant green.
Cool in the pan for 10 minutes, then move to a wire rack. Store in the refrigerator for up to 5 days or freeze for easy grab-and-go breakfasts.