Preheat the oven to 325°F (163°C). Line 16 muffin cups with paper liners. Do not grease the liners or pan.
Sift ¼ cup (50 g) superfine sugar, the flour, cornstarch, and salt into a bowl. Repeat the sifting two more times, for a total of three siftings. This helps the dry ingredients fold more easily into the whipped egg whites.
¾ cup (150 g) superfine sugar, 7 tbsp (55 g) all-purpose flour, 1 tbsp (8 g) cornstarch, ⅛ tsp (0.75 g) table salt
In a large bowl, beat the egg whites, warm water, and cream of tartar until foamy. Gradually add the remaining ½ cup (100 g) superfine sugar while beating. Continue beating until the egg whites hold soft peaks, then beat in the vanilla extract.
¾ cup (6.3 oz /180 g) freshly separated egg , 1 tbsp (15 ml) warm water, ¾ tsp (2.5 g) cream of tartar, 1¼ tsp (6 ml) vanilla extract
Using a rubber spatula, gently fold the sifted dry ingredients into the egg whites one-third at a time. Fold just until no streaks of flour remain, being careful not to deflate the batter..
Divide the batter evenly among the prepared muffin cups, filling each about three-quarters full.
Bake for 18 to 25 minutes, rotating the pans halfway through, until the tops are lightly golden and a toothpick inserted into the center comes out clean.
Let the cupcakes cool in the pan for 5 minutes, then carefully transfer them to a wire rack to cool completely.
To make the whipped cream, beat the heavy cream, confectioners' sugar, and vanilla until stiff peaks form. 1½ cups (360 ml) heavy whipped cream, ¼ cup (30 g) confectioners' sugar, ½ tsp (2.5 ml) vanilla extract
Once the cupcakes are completely cool, spoon or pipe the whipped cream onto each cupcake and finish with fresh berries before serving.
2 cup (240 g) fresh berries such as blueberries and raspberries