Preheat your waffle iron. Turn it on to its highest setting and let it heat up fully while you prepare the batter. You will hear a faint click when it reaches temperature, and a drop of water will sizzle and dance on the surface.

Whisk the dry ingredients together. In a large bowl, combine the flour, sugar, baking powder, salt, and cinnamon if using. Whisk until they are evenly distributed; the mixture should look pale and uniform.

Separate the eggs. Crack your eggs, placing the yolks into a separate small bowl and the whites into a clean, grease-free mixing bowl. Set the whites aside for a moment.

Make the batter base. In a jug or another bowl, whisk together the milk, melted butter, egg yolks, and vanilla extract until smooth. Pour this wet mixture into the dry ingredients and stir with a wooden spoon until just combined. The batter will look a little lumpy — do not overmix it, or your waffles will be tough.

Whip the egg whites. Using a clean whisk or electric beaters, whip the egg whites until they form stiff peaks. You should be able to turn the bowl upside down without the whites sliding out, and they will look glossy and cloud-like.

Fold the whites in. Gently fold a third of the whipped whites into the batter to lighten it, then carefully fold in the rest. The batter should become airy and billowy, with no visible streaks of white. You will smell the vanilla and butter even before it hits the iron.

Cook the waffles. Lightly grease the hot waffle iron with a little extra butter. Pour a ladleful of batter onto the centre of the iron — it should spread to the edges as you close the lid. Cook until the steam visibly reduces and the waffle is a deep, golden brown. The iron will release the waffle easily when it is ready; if it sticks, give it another minute.

Keep them warm. Transfer the cooked waffle to a wire rack set over a baking tray in a low oven (about 100°C) to keep it crisp while you cook the remaining batter. Repeat with the rest of the batter, lightly greasing the iron between batches.