Preheat the waffle iron. Set it to medium-high.
Lightly oil or spray it so the batter doesn’t stick.
Mix dry ingredients. In a bowl, whisk oat flour, whey, cornstarch, baking powder, baking soda, and salt until well combined.
Mix wet ingredients. In another bowl, whisk the egg, milk, Greek yogurt, maple syrup, vanilla, and melted butter/oil until smooth.
Combine gently. Pour wet into dry and stir until just combined. The batter should be thick but pourable. If it’s too thick, add 1–2 tablespoons milk.
If too thin, sprinkle in a little oat flour.
Fold in chocolate chips. Use a spatula and avoid overmixing to keep the texture light.
Rest the batter for 3–5 minutes. This helps the oats hydrate and the leavening activate for better lift.
Cook. Add batter to the hot iron (don’t overfill). Close and cook until deeply golden and crisp, usually 3–5 minutes depending on your iron.
Hold crisp. Place finished waffles on a wire rack instead of stacking. This keeps steam from softening them.
Serve. Top with Greek yogurt, fresh berries, a drizzle of maple syrup, or a smear of almond butter.
A sprinkle of flaky salt over the chocolate chips is a nice touch.