In a medium bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon. I like to sift the baking powder first to remove any lumps—this ensures a more even rise and lighter, fluffier waffles. Make sure the cinnamon is evenly distributed throughout the dry mixture so every waffle has consistent flavor.

In a large bowl, whisk together the room temperature eggs, Greek yogurt, milk, and vanilla until smooth and well combined. The room temperature eggs help create a smoother batter that mixes more easily with the yogurt—this is worth waiting a few minutes for. Whisk until there are no visible yogurt lumps remaining, which should take about 1-2 minutes.

Pour the wet ingredient mixture from Step 2 into the bowl with the dry ingredient mixture from Step 1. Gently fold the ingredients together with a spatula until just combined—do not overmix. A few small lumps are perfectly fine; overmixing will develop too much gluten and result in tough, dense waffles instead of light and fluffy ones.

Preheat your waffle iron to medium-high heat for about 2-3 minutes until it's hot and steaming. Lightly oil the top and bottom plates with cooking spray or a neutral oil to prevent sticking. Pour about 1/2 to 3/4 cup of batter into the center of the waffle iron (depending on your machine size) and close the lid. Cook for approximately 2 minutes, or until the waffle is golden brown and releases easily from the iron—steam should stop venting from the sides when it's ready.

Remove the finished waffle to a plate and quickly re-oil the waffle iron before cooking the next batch. I've found that lightly oiling between each waffle prevents sticking better than doing it just once at the beginning. Repeat the cooking process with the remaining batter from Step 3 until all batter is used, which should yield about 8-10 waffles depending on your waffle iron size.