Prepare the Batter Base: In a medium bowl, whisk together the egg yolks, 15g of the caster sugar, milk, and vanilla extract until the mixture is pale yellow and smooth. The aroma of vanilla will begin to fill your kitchen. Gradually add the sifted plain flour and baking powder, whisking until just combined and there are no lumps; avoid overmixing. The batter should be thick but pourable.

Whip the Egg Whites: In a separate, very clean, large bowl (preferably a metal or glass one), add the egg whites and cream of tartar. Using a hand mixer or stand mixer, whisk on medium speed until soft peaks form, which might take a couple of minutes. The whites will transform from clear liquid to an opaque, foamy cloud. Gradually add the remaining 15g of caster sugar, continuing to whisk on high speed until stiff, glossy peaks form. When you lift the whisk, the meringue should hold its shape firmly and shine beautifully.

Gently Combine: Carefully add about a third of the whipped egg whites to the egg yolk batter. Fold it in gently with a spatula to lighten the batter, not worrying too much about perfection at this stage. Then, add the remaining egg whites and fold them in very carefully, using an under-and-over motion, until just combined. The mixture should retain as much air as possible, looking like a pale, airy cloud with a slight yellowish tint, and will smell subtly sweet and eggy. Do not overmix, or you'll deflate all that wonderful air.

Heat the Pan: Heat a non-stick frying pan or griddle over very low heat. It’s important to keep the temperature gentle. Lightly brush the pan with a tiny amount of neutral oil. You want the pan to be warm, not smoking hot.

Cook the Pancakes: Using a large spoon or an ice cream scoop, carefully drop generous dollops of the batter into the pan. Aim for thick, tall mounds. If you have metal ring moulds, you can use them to help the pancakes hold their shape; lightly oil the inside of the moulds and place them in the pan before filling. Add a tablespoon of water to the pan around the pancakes (but not on them) and immediately cover the pan with a lid. This creates steam, which helps the pancakes rise beautifully and cook through without burning. Cook for 4-5 minutes on the first side. You'll notice the sides setting and the top becoming slightly dry and bubbly, and a wonderful golden-brown colour will be visible around the edges.

Flip and Finish: Remove the lid, gently flip the pancakes (or remove the moulds and flip them), add another tablespoon of water to the pan, and cover again. Cook for another 3-4 minutes until they are golden brown on the second side, completely cooked through, and have risen to an impressive height. They should feel incredibly light and springy to the touch. Serve immediately, as their soufflé-like structure begins to deflate after a few minutes, though they remain utterly delicious!