01 - Preheat the waffle iron following the manufacturer's instructions.
02 - Pulse the rolled oats in a blender or food processor until finely ground.
03 - Mix ground oats, flour, brown sugar, baking powder, baking soda, salt, and cinnamon in a large bowl.
04 - Whisk eggs, milk, melted butter, and vanilla extract together in a separate bowl.
05 - Add the wet mixture to the dry ingredients and stir until just combined. Allow the batter to rest for 5 minutes to thicken slightly.
06 - Lightly grease the waffle iron with oil or non-stick spray.
07 - Pour about 1/2 cup of batter per waffle onto the preheated iron. Cook for 3 to 5 minutes, or until golden brown and crisp.
08 - Serve immediately with your choice of toppings, such as maple syrup, fresh fruit, or yogurt.