Preheat the oven to 160°C fan (180°C conventional / 350°F). Line a cupcake tin with 6 paper cases.
Sift the flour, icing sugar and cornflour together in a bowl three times over to ensure a superfine texture.
35 grams (2.5 level tbsps) Icing sugar, 30 grams (2.5 level tbsps) Plain flour, 1 teaspoon Cornflour
In a separate bowl, add the egg whites, cream of tartar and vanilla. Mix on medium speed until the mixture becomes white and foamy (about 2-3 minutes).
3 large Eggs, 1 teaspoon Vanilla extract, 0.5 teaspoon Cream of tartar
Gradually add the caster sugar one tablespoon at a time, beating well after each addition. Turn the mixer up and whisk until the mixture thickens up and resembles soft fluffy clouds. If you lift your mixer up the peaks should stand tall on the whisks with no curl. This will usually take around 5 minutes.
40 grams (2.5 level tbsps) Caster sugar
Fold the dry ingredients into the whipped egg whites in three stages. Use a rubber spatula and fold gently in a figure-of-eight motion to keep the mixture light and airy.
Spoon the mixture into cupcake cases, filling them right to the top.
Bake at 160°C for 16-18 minutes, or until the tops are golden and spring back when touched. Remove and leave to cool in the tin for 10 minutes, then transfer to a wire rack. The cupcakes will shrink as they cool down.