In a blender, combine rolled oats, baking powder, salt, and ground cinnamon. Blend on high until the mixture resembles a fine flour, about 30 seconds. Transfer to a mixing bowl and set aside.

In the same blender, add the mashed ripe bananas, eggs, melted coconut oil, maple syrup or honey, vanilla extract, and spinach. Blend until smooth and vibrant green, about 30-45 seconds.

Add the dry oat mixture back into the blender with the wet ingredients. Pulse briefly for about 10-15 seconds until just combined; do not overmix.

Preheat the waffle iron according to the manufacturer's instructions and lightly grease if necessary. Pour about 1/2 cup of batter into the hot waffle iron and cook for 4-6 minutes until golden brown and crisp.

As you finish cooking waffles, place them on a baking sheet lined with parchment paper and keep warm in a 200°F oven until ready to serve.

Enjoy warm, topped with fruits, yogurt, or maple syrup. Store leftovers in an airtight container in the fridge or freeze for later.