Add oats to a blender, and blend on high speed for 20-30 seconds, or until they form a flour-like consistency. Add in the baking powder, salt and cinnamon, and pulse for 5 more seconds to combine. Set aside.
In a large mixing bowl, whisk together the eggs until smooth. Then whisk in the milk and maple syrup until evenly combined.
Add the oatmeal mixture to the egg mixture, and stir together until evenly combined. Let the mixture rest for 5 minutes.
Then cook the batter according to your waffle maker's instructions.
Serve warm, topped with butter and extra maple syrup (or any of your favorite toppings).
Notes
*Most old-fashioned oats sold in stores are gluten-free, but be sure to check on the packaging to see that they are certified gluten-free just to be sure.