Turn on your waffle maker and allow it to fully preheat. Lightly grease it with cooking spray or oil.

In a large bowl, whisk together the eggs, Greek yogurt, milk, vanilla extract, and sweetener until smooth.

Add protein powder, oat flour, baking powder, and salt to the bowl. Stir gently until just combined. Avoid overmixing, as this can make the waffles dense.

The batter should be thick but pourable. Add a tablespoon of milk at a time if needed.

Pour the batter into the preheated waffle iron, spreading slightly. Cook according to your waffle maker’s instructions, usually 3–5 minutes, until golden and crisp.

Continue cooking until all batter is used, lightly greasing the waffle iron between batches if needed.

Remove waffles carefully and serve immediately or keep warm in a low oven.