Preheat the waffle iron hot. A hot iron is key to crisp edges. If your iron has settings, set it to medium-high.

Whisk dry ingredients. In a large bowl, combine flour, cornstarch, protein powder, sweetener, baking powder, baking soda, and salt. Break up any clumps.

Mix wet ingredients. In another bowl, whisk milk, Greek yogurt, eggs, oil, and vanilla until smooth.

Combine gently. Pour wet into dry and stir just until you don’t see dry flour. A few small lumps are fine. The batter should be pourable but not runny. If too thick, add 1–2 tbsp milk; if too thin, sprinkle in a bit more flour.

Rest the batter for 5 minutes. This hydrates the flour and helps the waffles rise and crisp.

Grease the iron. Lightly spray or brush with oil. Don’t overdo it—too much oil can make waffles soft.

Cook the waffles. Pour enough batter to cover the grid without overflowing. Close and cook until steam slows and the waffle is deep golden, 3–5 minutes depending on your iron.

Cool on a rack. Place finished waffles on a wire rack instead of stacking. This keeps them crisp.

Serve hot with your choice of toppings. Try berries, Greek yogurt, nut butter, a fried egg, or a drizzle of maple syrup.