In a large mixing bowl, beat the eggs with Greek yogurt, granulated sweetener and vanilla extract. Whisk until smooth.
Add oat flour, protein powder, baking powder and salt to the wet mixture. Stir until combined, the batter should be smooth and free of lumps.
Preheat the waffle iron according to the manufacturer’s instructions. Lightly grease it with cooking spray or with a small amount of melted butter or oil.
Pour a couple tablespoons of batter into waffle grids, spreading it evenly. Close the grids and cook until the waffles are golden brown and crisp, about 3-5 minutes, depending on your waffle iron.
Let cool for 5 to 10 minutes and serve with your favorite toppings.