Add the dry stuff to a blender: oats, baking powder and cinnamon.
Run the blender slowly up to medium-high and grind the oats into a flour. This will take about 30 seconds depending on how powerful your blender is.
Add that dry oat flour mixture you just made into a great big bowl.
Add the wet stuff to the now empty blender: Greek yogurt, eggs, milk, olive oil and vanilla.
Blend on medium until smooth and homogeneous.
Add the wet mixture to the dry mixture and stir or whisk together until smooth. There is no gluten here, so there is little chance to "over-mix" it. I let the oats sit then for a minute or two to absorb the liquid while the waffle irons heat up.
Add ½ cup of batter (or whatever your waffle iron says) to the hot waffle griddle. Cook and eat!
Notes
Recipe adapted from Chris Powell's on ABC's Good Morning America
Recipe by Whisk Together at https://www.whisktogether.com/2016/07/05/greek-yogurt-waffles/